U.S. patent application number 15/030681 was filed with the patent office on 2016-08-25 for multilayer film, optically anisotropic laminate, circular polarizer, organic electroluminescent display, and manufacturing methods.
This patent application is currently assigned to ZEON CORPORATION. The applicant listed for this patent is ZEON CORPORATION. Invention is credited to Hiromasa HASHIMOTO, Masakazu SAITO, Shunsuke YAMANAKA.
Application Number | 20160245972 15/030681 |
Document ID | / |
Family ID | 53004183 |
Filed Date | 2016-08-25 |
United States Patent
Application |
20160245972 |
Kind Code |
A1 |
YAMANAKA; Shunsuke ; et
al. |
August 25, 2016 |
MULTILAYER FILM, OPTICALLY ANISOTROPIC LAMINATE, CIRCULAR
POLARIZER, ORGANIC ELECTROLUMINESCENT DISPLAY, AND MANUFACTURING
METHODS
Abstract
A multilayer film including: a first long-length substrate; and
an optically anisotropic layer that is formed directly on the first
substrate and contains cured liquid-crystal molecules, wherein the
first substrate has an orientation-controlling force caused by
stretching, and a slow axis of the first substrate is different
from a lengthwise direction of the first substrate; an optically
anisotropic laminate, a circular polarizing plate, and an organic
EL display device having the anisotropic layer; as well as
manufacturing method thereof.
Inventors: |
YAMANAKA; Shunsuke; (Tokyo,
JP) ; SAITO; Masakazu; (Tokyo, JP) ;
HASHIMOTO; Hiromasa; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ZEON CORPORATION |
Tokyo |
|
JP |
|
|
Assignee: |
ZEON CORPORATION
Tokyo
JP
|
Family ID: |
53004183 |
Appl. No.: |
15/030681 |
Filed: |
October 28, 2014 |
PCT Filed: |
October 28, 2014 |
PCT NO: |
PCT/JP2014/078646 |
371 Date: |
April 20, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 5/3016 20130101;
B32B 23/08 20130101; G02F 1/13363 20130101; B32B 27/08 20130101;
H01L 51/5281 20130101; B32B 2457/206 20130101; B32B 23/20 20130101;
B32B 2307/42 20130101; G02B 5/3083 20130101; G02B 5/30
20130101 |
International
Class: |
G02B 5/30 20060101
G02B005/30; H01L 51/52 20060101 H01L051/52 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 28, 2013 |
JP |
2013-223699 |
Aug 29, 2014 |
JP |
2014-175917 |
Claims
1. A multilayer film comprising: a first long-length substrate; and
an optically anisotropic layer that is formed directly on the first
substrate and contains cured liquid-crystal molecules, wherein the
first substrate has an orientation-controlling force caused by
stretching, and a slow axis of the first substrate is different
from a lengthwise direction of the first substrate.
2. The multilayer film according to claim 1, wherein the slow axis
of the first substrate and the lengthwise direction of the first
substrate form an angle of 10.degree. to 90.degree..
3. The multilayer film according to claim 2, wherein the slow axis
of the first substrate and the lengthwise direction of the first
substrate form an angle of 40.degree. to 50.degree..
4. The multilayer film according to claim 1, wherein the first
substrate is a film of a resin having a positive intrinsic
birefringence.
5. The multilayer film according to any claim 1, wherein the first
substrate is a film of a resin containing an alicyclic
structure-containing polymer or a film of cellulose ester.
6. The multilayer film according to claim 1, wherein the first
substrate is a stretched film obtained by widthwise stretching or
diagonal stretching.
7. The multilayer film according to claim 1, wherein the optically
anisotropic layer has inverse wavelength distribution.
8. The multilayer film according to claim 1, wherein the optically
anisotropic layer is a .lamda./4 wave plate.
9. The multilayer film according to claim 1, wherein the optically
anisotropic layer is a .lamda./2 wave plate.
10. The multilayer film according to claim 1, wherein the optically
anisotropic layer has a thickness of 5 .mu.m or less.
11. The multilayer film according to claim 1, wherein the cured
liquid-crystal molecules of the optically anisotropic layer have
homogeneous orientation regularity in substantially a same
direction as a direction of the slow axis of the first
substrate.
12. The multilayer film according to claim 1, wherein the optically
anisotropic layer formed on the first substrate is obtained by
applying onto the first substrate a liquid crystal composition
containing a polymerizable liquid crystal compound to form a layer
of the liquid crystal composition, giving homogeneous orientation
to the polymerizable liquid crystal composition in the layer, the
orientation being in substantially a same direction as a direction
of the slow axis of the first substrate, and polymerizing the
polymerizable liquid crystal compound to form the cured
liquid-crystal molecules.
13. The multilayer film according to claim 1, wherein the first
substrate has a birefringence .DELTA.n of 0.000050 or more.
14. An optically anisotropic laminate obtained by separating the
optically anisotropic layer from the multilayer film according to
claim 1 and attaching the optically anisotropic layer to a second
long-length substrate.
15. A circular polarizing plate obtained by attaching an optically
anisotropic layer to a long-length linear polarizer by a
roll-to-roll process, wherein the optically anisotropic layer is a
layer separated from the multilayer film according to claim 1.
16. An organic electroluminescent display device comprising the
circular polarizing plate according to claim 15.
17. A method for manufacturing the multilayer film according to
claim 1, comprising: a step (I) of feeding out a long-length first
substrate in the lengthwise direction, the first substrate having
an orientation-controlling force caused by stretching, wherein a
slow axis of the first substrate is different from a lengthwise
direction of the first substrate; a step (II) of directly applying
onto a surface of the fed-out first substrate a liquid crystal
composition containing a polymerizable liquid crystal compound to
form a layer of the liquid crystal composition; a step (III) of
giving orientation to the polymerizable liquid crystal compound in
the layer of the liquid crystal composition; and a step (IV) of
polymerizing the polymerizable liquid crystal compound to form
cured liquid-crystal molecules.
18. The method for manufacturing the multilayer film according to
claim 17, wherein an applying direction of the liquid crystal
composition is different from an orientation direction of the
polymerizable liquid crystal compound.
Description
FIELD
[0001] The present invention relates to a multilayer film that has
an optically anisotropic layer and an optically anisotropic
laminate. The present invention also relates to a circular
polarizing plate having the optically anisotropic layer, an organic
electroluminescent display device, and a manufacturing method.
BACKGROUND
[0002] A phase difference plate is widely used as a component of
display devices such as a liquid crystal display device and an
organic electroluminescent (hereinafter sometimes referred to as
"organic EL") display device. A phase difference plate used in the
display device may be required to uniformly express a desired phase
difference of .lamda./4, .lamda./2, or the like in the entire
wavelength region for displaying (usually visible region), to
thereby expressing the effect in the entire wavelength region for
displaying.
[0003] If it is possible to continuously manufacture such a phase
difference plate as a long-length film having a desired width in a
manufacture line, from which phase difference plates of a
rectangular shape that corresponds to a rectangular display surface
of the display device are then cut out, this process would enable
efficient manufacturing. Further, if it is possible to perform such
cutting such that the edges of the rectangular shape correspond to
directions close to directions parallel to the lengthwise direction
and widthwise direction of the long-length phase difference plate,
this process would enables more efficient manufacturing.
[0004] The phase difference plate in the display device may be
required to have a slow axis at a certain angle, such as
15.degree., 45.degree., or 75.degree., relative to a transmission
axis of a co-used polarizing plate. For example, when a linear
polarizer and a .lamda./4 wave plate are used in combination to
express an anti-reflection function, the phase difference plate is
required to have a slow axis at an angle of 45.degree. relative to
a transmission axis of the linear polarizer. Regarding polarization
axes of a polarizing plate, a transmission axis of the polarizing
plate in many cases is in a direction parallel to a widthwise or
lengthwise side of a rectangular display surface of the display
device. In manufacturing of a linear polarizer as a long-length
film, a linear polarizer having a transmission axis in a direction
parallel to or orthogonal to the lengthwise direction, particularly
in a direction orthogonal to the lengthwise direction, can be
easily manufactured. Therefore, if it is possible to manufacture a
long-length phase difference plate having a slow axis at a certain
angle such as 15.degree., 45.degree., or 75.degree. relative to the
widthwise direction, such a manufacturing process is very
advantageous for manufacturing the phase difference plates for the
display device.
[0005] As one of methods for obtaining the phase difference plate,
there is known a method of using a compound capable of exhibiting a
liquid crystal phase in which such a compound is molded into a
solid film while keeping the state of the liquid crystal phase.
Specific examples of the method may include a method in which a
composition containing a polymerizable liquid crystal compound that
is polymerizable and capable of exhibiting a liquid crystal phase
is applied onto a surface of an appropriate substrate to form a
layer, and orientation is given to the polymerizable compound in
the layer and then polymerized while keeping the oriented state, to
thereby form an optically anisotropic film. According to such a
method, a phase difference plate that uniformly expresses phase
difference in the plane can be obtained. When the polymerizable
liquid crystal compound is appropriately selected, a phase
difference plate that causes a uniform phase difference at a
visible light wavelength region can be obtained (for example,
Patent Literature 1).
[0006] As a method for giving orientation to such a compound
capable of exhibiting a liquid crystal phase, a method in which an
orientation-controlling force is imparted to a surface of a
substrate, a composition containing a compound capable of
exhibiting a liquid crystal phase is then applied onto the surface
and placed under conditions suitable for giving orientation is
usually performed. Examples of the method for imparting an
orientation-controlling force to a surface of a substrate may
include a method through rubbing (for example, Patent Literatures 2
to 4) and a method of optical orientation (for example, Patent
Literatures 5 and 6). In addition, a method in which a film that
has been subjected to a stretching treatment is used as a substrate
to give orientation to a liquid crystal compound on a film is known
(for example, Patent Literatures 7 to 9).
CITATION LIST
Patent Literature
[0007] Patent Literature 1: Japanese Patent Application Laid-Open
No. Hei. 11-52131 A
[0008] Patent Literature 2: Japanese Patent Application Laid-Open
No. Hei. 8-160430 A
[0009] Patent Literature 3: Japanese Patent Application Laid-Open
No. 2000-267105 A
[0010] Patent Literature 4: Japanese Patent Application Laid-Open
No. 2002-6322 A
[0011] Patent Literature 5: Japanese Patent No. 2980558 B
[0012] Patent Literature 6: Japanese Patent Application Laid-Open
No. Hei. 11-153712 A
[0013] Patent Literature 7: Japanese Patent Application Laid-Open
No. Hei. 3-9325 A
[0014] Patent Literature 8: Japanese Patent Application Laid-Open
No. Hei. 4-16919 A
[0015] Patent Literature 9: Japanese Patent Application Laid-Open
No. 2003-207641 A
SUMMARY
Technical Problem
[0016] However, operation of rubbing may easily generate static
electricity during the treatment process. Such generation of static
electricity causes problems such as attachment of a heterogeneous
matter. Further, quality of the product is deteriorated due to
occurrence of orientation defects. Further, when the rubbing is
continuously performed in a diagonal direction on a long-length
substrate, there is a problem in which it is very difficult to
exactly control the orientation direction. Further, when the
orientation-controlling force is imparted by optical orientation,
there are problems of high cost and low processing rate.
[0017] Therefore, an object of the present invention is to provide
a multilayer film and an optically anisotropic laminate that have
an optically anisotropic layer, that can be used for a material for
a phase difference plate such as a .lamda./2 wave plate and a
.lamda./4 wave plate, that uniformly expresses phase difference in
the plane, that can be efficiently manufactured, and that has a
reduced number of defects due to generation of a heterogeneous
matter, and a method for manufacturing the same.
[0018] Another object of the present invention is to provide a
circular polarizing plate and an organic electroluminescent display
device that can be efficiently manufactured and that have a reduced
number of defects due to generation of a heterogeneous matter.
Solution to Problem
[0019] The present inventor has studied to solve the aforementioned
problems. As a result, the inventor has conceived of use of a
substrate having a slow axis in a direction that is different from
the lengthwise direction thereof. The inventor has found out that,
when an optically anisotropic layer containing cured liquid-crystal
molecules with orientation regularity is formed directly on such a
substrate, the aforementioned problems can be solved. Thus, the
present invention has been completed.
[0020] Accordingly, the present invention provides the following.
[0021] (1) A multilayer film comprising:
[0022] a first long-length substrate; and
[0023] an optically anisotropic layer that is formed directly on
the first substrate and contains cured liquid-crystal molecules,
wherein
[0024] the first substrate has an orientation-controlling force
caused by stretching, and
[0025] a slow axis of the first substrate is different from a
lengthwise direction of the first substrate. [0026] (2) The
multilayer film according to (1), wherein the slow axis of the
first substrate and the lengthwise direction of the first substrate
form an angle of 10.degree. to 90.degree.. [0027] (3) The
multilayer film according to (2), wherein the slow axis of the
first substrate and the lengthwise direction of the first substrate
form an angle of 40.degree. to 50.degree.. [0028] (4) The
multilayer film according to any one of (1) to (3), wherein the
first substrate is a film of a resin having a positive intrinsic
birefringence. [0029] (5) The multilayer film according to any one
of (1) to (4), wherein the first substrate is a film of a resin
containing an alicyclic structure-containing polymer or a film of
cellulose ester. [0030] (6) The multilayer film according to any
one of (1) to (5), wherein the first substrate is a stretched film
obtained by widthwise stretching or diagonal stretching. [0031] (7)
The multilayer film according to any one of (1) to (6), wherein the
optically anisotropic layer has inverse wavelength distribution.
[0032] (8) The multilayer film according to any one of (1) to (7),
wherein the optically anisotropic layer is a .lamda./4 wave plate.
[0033] (9) The multilayer film according to any one of (1) to (7),
wherein the optically anisotropic layer is a .lamda./2 wave plate.
[0034] (10)The multilayer film according to any one of (1) to (9),
wherein the optically anisotropic layer has a thickness of 5 .mu.m
or less. [0035] (11) The multilayer film according to any one of
(1) to (10), wherein the cured liquid-crystal molecules of the
optically anisotropic layer have homogeneous orientation regularity
in substantially a same direction as a direction of the slow axis
of the first substrate. [0036] (12) The multilayer film according
to any one of (1) to (11), wherein the optically anisotropic layer
formed on the first substrate is obtained by
[0037] applying onto the first substrate a liquid crystal
composition containing a polymerizable liquid crystal compound to
form a layer of the liquid crystal composition,
[0038] giving homogeneous orientation to the polymerizable liquid
crystal composition in the layer, the orientation being in
substantially a same direction as a direction of the slow axis of
the first substrate, and
[0039] polymerizing the polymerizable liquid crystal compound to
form the cured liquid-crystal molecules. [0040] (13) The multilayer
film according to any one of (1) to (12), wherein the first
substrate has a birefringence .DELTA.n of 0.000050 or more. [0041]
(14) An optically anisotropic laminate obtained by separating the
optically anisotropic layer from the multilayer film according to
any one of (1) to (13) and
[0042] attaching the optically anisotropic layer to a second
long-length substrate. [0043] (15) A circular polarizing plate
obtained by attaching an optically anisotropic layer to a
long-length linear polarizer by a roll-to-roll process, wherein
[0044] the optically anisotropic layer is a layer separated from
the multilayer film according to any one of (1) to (13). [0045]
(16) An organic electroluminescent display device comprising the
circular polarizing plate according to (15). [0046] (17) A method
for manufacturing the multilayer film according to any one of (1)
to (13), comprising:
[0047] a step (I) of feeding out a long-length first substrate in
the lengthwise direction, the first substrate having an
orientation-controlling force caused by stretching, wherein a slow
axis of the first substrate is different from a lengthwise
direction of the first substrate;
[0048] a step (II) of directly applying onto a surface of the
fed-out first substrate a liquid crystal composition containing a
polymerizable liquid crystal compound to form a layer of the liquid
crystal composition;
[0049] a step (III) of giving orientation to the polymerizable
liquid crystal compound in the layer of the liquid crystal
composition; and
[0050] a step (IV) of polymerizing the polymerizable liquid crystal
compound to form cured liquid-crystal molecules. [0051] (18) The
method for manufacturing the multilayer film according to (17),
wherein an applying direction of the liquid crystal composition is
different from an orientation direction of the polymerizable liquid
crystal compound.
[0052] Further, the present application discloses the following.
[0053] (19) A resin film formed on a long-length substrate, the
film comprising a cured liquid-crystal molecule, wherein:
[0054] the substrate has a slow axis in a direction different from
the widthwise direction thereof; and
[0055] the cured liquid-crystal molecule has homogeneous
orientation regularity in substantially the same direction as the
slow axis direction of the substrate. [0056] (20) The resin film
according to (19), wherein:
[0057] the forming of the resin film on the substrate
comprises:
[0058] applying onto the substrate a liquid crystal composition
containing a polymerizable liquid crystal compound to form a layer
of the liquid crystal composition;
[0059] giving homogeneous orientation to the polymerizable liquid
crystal compound in the layer, the orientation being in
substantially the same direction as the direction of slow axis of
the substrate, and
[0060] polymerizing the polymerizable liquid crystal compound to
form the cured liquid-crystal molecule. [0061] (21) The resin film
according to (19) or (20), wherein the substrate has a
birefringence .DELTA.n of 0.000050 or more. [0062] (22) The resin
film according to any one of (19) to (21) having inverse wavelength
distribution. [0063] (23) The resin film according to any one of
(19) to (22), wherein the substrate is a film of a resin containing
an alicyclic structure-containing polymer or a film of cellulose
ester. [0064] (24) A .lamda./4 wave plate comprising the resin film
according to any one of (19) to (23). [0065] (25) The .lamda./4
wave plate according to (24) further comprising the substrate.
[0066] (26) A circular polarizing plate comprising the .lamda./4
wave plate according to (24) or (25). [0067] (27) An organic
electroluminescent display device comprising the circular
polarizing plate according to (26). [0068] (28) A method for
manufacturing a resin film containing a cured liquid-crystal
molecule, the method comprising:
[0069] applying onto a substrate a liquid crystal composition
containing a polymerizable liquid crystal compound to form a layer
of the liquid crystal composition;
[0070] giving homogeneous orientation to the polymerizable liquid
crystal compound in the layer, the orientation being in
substantially the same direction as the direction of slow axis of
the substrate; and
[0071] a step of polymerizing the polymerizable liquid crystal
compound to form the cured liquid-crystal molecule, wherein:
[0072] the substrate is a long-length substrate, and has a slow
axis in a direction different from the widthwise direction thereof;
and
[0073] the cured liquid-crystal molecules has homogeneous
orientation regularity in substantially the same direction as the
slow axis direction of the substrate.
Advantageous Effects of Invention
[0074] The multilayer film and the optically anisotropic laminate
of the present invention can provide an optically anisotropic layer
that is capable of being used for a material for a phase difference
plate such as a .lamda./2 wave plate and a .lamda./4 wave plate,
that uniformly expresses phase difference in the plane, that can be
efficiently manufactured, and that has a reduced number of defects
due to generation of a heterogeneous matter. According to the
manufacturing method of the present invention, the multilayer film
of the present invention can be efficiently manufactured.
[0075] Furthermore, when an optically anisotropic layer having
inverse wavelength distribution is formed using a polymerizable
liquid crystal compound having inverse wavelength distribution as a
material for cured liquid-crystal molecules, an optical material
that has high manufacturing efficiency by diagonal stretching, high
degree of design freedom of slow axis direction, uniform properties
in the plane, a reduced number of defects due to a heterogeneous
matter, and usefulness by virtue of inverse wavelength
distribution, all of which are at high levels, can be provided.
[0076] The circular polarizing plate and the organic
electroluminescent display device of the present invention are a
circular polarizing plate and an organic electroluminescent display
device that have uniform properties, that can be efficiently
manufactured, and that have a reduced number of defects due to
generation of a heterogeneous matter.
BRIEF DESCRIPTION OF DRAWINGS
[0077] FIG. 1 is a photograph showing a specific example of an
optically anisotropic layer having orientation defects.
[0078] FIG. 2 is a graph showing results of measurement of
reflectance of light incident on a surface on a polarizer side of a
laminate for evaluation of a circular polarizing plate and
calculation of reflection brightness from the measured
reflectance.
DESCRIPTION OF EMBODIMENTS
[0079] Hereinafter, the present invention will be described in
detail with reference to examples and embodiments, but the present
invention is not limited to the following examples and embodiments
and may be implemented with any optional modifications without
departing from the scope of claims of the present invention and
equivalents thereto.
[0080] In this application, a plate-shaped member such as a
"polarizing plate", a ".lamda./2 wave plate", a ".lamda./4 wave
plate", and a "phase difference plate", is not limited to a rigid
member, and may have a film shape and flexibility.
[0081] [1. Multilayer Film]
[0082] The multilayer film of the present invention comprises a
first long-length substrate and an optically anisotropic layer that
is formed directly on the first substrate and contains cured
liquid-crystal molecules.
[0083] The "cured liquid-crystal molecules" herein means molecules
of a compound in a solidified product that is obtained by
solidification wherein the compound that is capable of exhibiting a
liquid crystal phase is solidified while keeping the state of
exhibiting the liquid crystal phase. Examples of the cured
liquid-crystal molecules may include a polymer obtained by
polymerizing a polymerizable liquid crystal compound. Unless
otherwise specified, this specific optically anisotropic layer
containing the cured liquid-crystal molecules is simply referred to
as "optically anisotropic layer" in the following description.
[0084] [1.1. First Substrate]
[0085] The first substrate used in the present invention is a
long-length substrate. The "long-length" herein means a shape
having a length that is at least 5 times or more longer than the
width, and preferably 10 times or more longer than the width, and
specifically means a shape of a film having such a length that the
film can be wound up into a roll shape for storage or
transport.
[0086] The first substrate used in the present invention has a slow
axis in a direction different from the lengthwise direction of the
substrate. Unless otherwise specified, the directions of slow axes
of the first substrate and the optically anisotropic layer herein
represent a direction of slow axis in an in-plane direction.
[0087] Unless otherwise specified, an angle representing the
direction of slow axis of the substrate herein is with reference to
the widthwise direction of the substrate, and represents an angle
relative to this direction.
[0088] The angle formed between the slow axis of the first
substrate and the lengthwise direction of the first substrate may
be specifically 10.degree. to 90.degree.. When the first substrate
has a slow axis at an angle falling within such a range, the
multilayer film of the present invention may serve as a material
capable of efficiently manufacturing a circular polarizing plate,
and the like.
[0089] In a certain aspect, the angle formed between the slow axis
of the first substrate and the lengthwise direction of the first
substrate is preferably 30.degree. to 80.degree., and particularly
preferably 40.degree. to 50.degree.. When this angle relationship
is satisfied, the multilayer film of the present invention may be a
material capable of efficiently manufacturing a specific circular
polarizing plate. Specifically, a circular polarizing plate having
a linear polarizer and one layer of phase difference plate can be
efficiently manufactured.
[0090] More specifically, when the angle formed between the slow
axis of the first substrate and the lengthwise direction of the
first substrate preferably falls within a specific range of
15.degree..+-.5.degree., 45.degree..+-.5.degree.,
67.5.+-.5.degree., or 75.degree..+-.5.degree., more preferably
15.degree..+-.4.degree., 45.degree..+-.4.degree.,
67.5.degree..+-.4.degree., or 75.degree..+-.4.degree., and further
preferably 15.degree..+-.3.degree., 45.degree..+-.3.degree.,
67.5.degree..+-.3.degree., or 75.degree..+-.3.degree., the
multilayer film of the present invention may serve as a material
capable of efficiently manufacturing a specific circular polarizing
plate.
[0091] The material for the first substrate is not particularly
limited. Various resins capable of imparting an
orientation-controlling force to the surface of the substrate by
imparting birefringence may be used. Examples of the resins may
include resins containing various types of polymers. Examples of
the polymers may include an alicyclic structure-containing polymer,
a cellulose ester, a polyvinyl alcohol, a polyimide,
UV-transmitting acrylic, a polycarbonate, a polysulfone, a
polyether sulfone, an epoxy polymer, a polystyrene, and
combinations thereof. Among these, an alicyclic
structure-containing polymer and a cellulose ester are preferred,
and an alicyclic structure-containing polymer is more preferred
from the viewpoint of transparency, low hygroscopicity, size
stability, and low weight.
[0092] It is preferable that the first substrate is a film of a
resin having positive intrinsic birefringence. When the resin
having a positive intrinsic birefringence is used as the material,
a first substrate having favorable properties such as high
orientation-controlling force, high strength, and low cost can be
easily obtained.
[0093] The alicyclic structure-containing polymer is an amorphous
polymer having an alicyclic structure in a repeating unit. Either a
polymer containing an alicyclic structure in a main chain or a
polymer containing an alicyclic structure in a side chain may be
used. Examples of the alicyclic structure may include a cycloalkane
structure and a cycloalkene structure. A cycloalkane structure is
preferred from the viewpoint of thermal stability.
[0094] The number of carbon atoms constituting one repeating unit
having the alicyclic structure is not particularly limited, but is
usually 4 to 30, preferably 5 to 20, and more preferably 6 to
15.
[0095] The ratio of the repeating unit having the alicyclic
structure in the alicyclic structure-containing polymer is
appropriately selected depending on the purposes of use, and is
usually 50% by weight or more, preferably 70% by weight or more,
and more preferably 90% by weight or more.
[0096] When the ratio of the repeating unit having the alicyclic
structure is too low, the heat resistance of the film may
deteriorate.
[0097] Specific examples of the alicyclic structure-containing
polymer may include (1) a norbornene polymer, (2) a monocyclic
olefin polymer, (3) a cyclic conjugated diene polymer, and (4) a
vinyl alicyclic hydrocarbon polymer, as well as hydrogenated
products thereof.
[0098] Among these, a norbornene polymer and a hydrogenated product
thereof are more preferred from the viewpoint of transparency and
moldability.
[0099] Examples of the norbornene polymer may include a
ring-opening polymer of a norbornene monomer, a ring-opening
copolymer of a norbornene monomer with a ring-opening polymerizable
monomer other than the norbornene monomer, and a hydrogenated
product thereof; an addition polymer of a norbornene monomer, and
an addition copolymer of a norbornene monomer with a
copolymerizable monomer other than the norbornene monomer.
[0100] Among these, a hydrogenated product of ring-opening polymer
of a norbornene monomer is the most preferred from the viewpoint of
transparency.
[0101] The alicyclic structure-containing polymer is, for example,
selected from known polymers disclosed in Japanese Patent
Application Laid-Open No. 2002-321302 A and the like.
[0102] The glass transition temperature of the alicyclic
structure-containing polymer is preferably 80.degree. C. or higher,
and more preferably within a range of 100 to 250.degree. C.
[0103] The alicyclic structure-containing polymer having a glass
transition temperature falling within this range is not deformed or
does not generate stress during use at high temperature, and has
excellent durability.
[0104] The molecular weight of the alicyclic structure-containing
polymer is a weight average molecular weight (Mw) measured by gel
permeation chromatography (hereinafter abbreviated as "GPC") using
cyclohexane (when a resin is not dissolved therein, toluene) as a
solvent in terms of polyisoprene (in terms of polystyrene when the
solvent is toluene). The molecular weight is usually 10,000 to
100,000, preferably 25,000 to 80,000, and more preferably 25,000 to
50,000.
[0105] When the weight average molecular weight thereof falls
within such a range, the mechanical strength and molding
processability of the film are highly balanced. Therefore, this is
suitable.
[0106] The molecular weight distribution (weight average molecular
weight (Mw)/number average molecular weight (Mn)) of the alicyclic
structure-containing polymer is not particularly limited, and
usually falls within a range of 1 to 10, preferably 1 to 4, and
more preferably 1.2 to 3.5.
[0107] In a resin containing the alicyclic structure-containing
polymer, the amount of a resin component having a molecular weight
of 2,000 or less (i.e., oligomer component) contained therein is
preferably 5% by weight or less, more preferably 3% by weight or
less, and further preferably 2% by weight or less.
[0108] When the amount of the oligomer component falls within the
aforementioned range, the generation of fine convex portions on a
surface is decreased, the unevenness of thickness is decreased, and
the surface profile evenness is improved.
[0109] In order to decrease the amount of the oligomer component,
selection of a polymerization catalyst and a hydrogenation
catalyst, reaction conditions of polymerization, hydrogenation, and
the like, temperature conditions in a process of molding the resin
as a molding material into pellets, and the like may be
optimized.
[0110] The amount of the oligomer component may be measured by GPC
as described above.
[0111] When the resin containing the alicyclic structure-containing
polymer is used as the material for the first substrate, the
thickness of the first substrate is not particularly limited. The
thickness of the first substrate is usually 1 to 1,000 .mu.m,
preferably 5 to 300 and more preferably 30 to 100 .mu.m from the
viewpoint of increased productivity and facilitation of reduction
in thickness and weight saving.
[0112] The resin containing the alicyclic structure-containing
polymer may be composed only of the alicyclic structure-containing
polymer, or may contain any compounding agent as long as the
effects of the present invention are not significantly impaired.
The ratio of the alicyclic structure-containing polymer in the
resin containing the alicyclic structure-containing polymer is
preferably 70% by weight or more, and more preferably 80% by weight
or more.
[0113] Specific suitable examples of the resin containing the
alicyclic structure-containing polymer may include "ZEONOR 1420 and
ZEONOR 1420R" available from ZEON CORPORATION.
[0114] A typical example of the cellulose ester is a lower fatty
acid ester of cellulose (for example, cellulose acetate, cellulose
acetate butyrate, and cellulose acetate propionate). A lower fatty
acid means a fatty acid having 6 or less carbon atoms in one
molecule. Cellulose acetate includes triacetylcellulose (TAC) and
cellulose diacetate (DAC).
[0115] The acetylation degree of cellulose acetate is preferably 50
to 70%, and particularly preferably 55 to 65%. The weight average
molecular weight of cellulose acetate is preferably 70,000 to
120,000, and particularly preferably 80,000 to 100,000. The
aforementioned cellulose acetate may be partially esterified with
not only acetic acid but also a fatty acid such as propionic acid
and butyric acid as long as the aforementioned acetylation degree
is satisfied. The resin constituting the first substrate may
contain cellulose acetate in combination with a cellulose ester
other than cellulose acetate (cellulose propionate, cellulose
butyrate, etc.). In this case, it is preferable that the total
amount of the cellulose esters satisfies the aforementioned
acetylation degree.
[0116] When a film of triacetylcellulose is used as the first
substrate, it is particularly preferable that such a film is a
triacetylcellulose film formed using triacetylcellulose dope that
is prepared by dissolving triacetylcellulose in a solvent
essentially free of dichloromethane by a low-temperature
dissolution method or a high-temperature dissolution method from
the viewpoint of environmental conservation. The film of
triacetylcellulose may be prepared by a co-casting method. The
co-casting method may be performed by dissolving raw material
flakes of triacetylcellulose in a solvent, and if necessary, adding
any additive to prepare a solution (dope), casting the dope on a
support from dope supply means (die), drying the cast product to
some extent, separating the cast product as a film from the support
when rigidity is imparted, and further drying the film to remove
the solvent. Examples of the solvent for dissolving the raw
material flakes may include a halogenated hydrocarbon
(dichloromethane, etc.), an alcohol (methanol, ethanol, butanol,
etc.), an ester (methyl formate, methyl acetate, etc.), and an
ether (dioxane, dioxolane, diethyl ether, etc.). Examples of the
additive added to the dope may include a retardation-increasing
agent, a plasticizer, an ultraviolet absorber, a deterioration
preventing agent, a lubricant, and a separation promoter. Examples
of the support on which the dope is cast may include a horizontal
endless metal belt and a rotation drum. For casting, a single dope
may be cast in a single layer, or co-cast in a plurality of layers.
In casting in a plurality of layers, for example, a plurality of
dopes may be successively cast so that a layer of low-concentration
cellulose ester dope and layers of high-concentration cellulose
ester dope in contact with the front side and back side of the
layer are formed. Examples of means for drying the film to remove
the solvent may include means for conveying the film to pass the
film through a drying unit in which the interior portion is placed
under conditions suitable for drying.
[0117] Preferable examples of the film of triacetylcellulose may
include any known films such as TAC-TD80U (available from Fuji
Photo Film Co., Ltd.), and a film disclosed in JIII journal of
technical disclosure No. 2001-1745. The thickness of the film of
triacetylcellulose is not particularly limited, and is preferably
30 to 150 .mu.m, more preferably 40 to 130 and further preferably
70 to 120 .mu.m.
[0118] The first substrate has an orientation-controlling force
caused by stretching. Further, the first substrate has the slow
axis in a direction different from the lengthwise direction of the
first substrate.
[0119] Such a first substrate may be prepared by stretching a film
such as the film made of the aforementioned material, to impart
optical anisotropy. The stretching direction may be appropriately
set depending on a desired orientation direction required for the
optically anisotropic layer. The stretching may be performed by
only diagonal stretching, only widthwise stretching (stretching in
the widthwise direction of the first substrate), or a combination
of diagonal stretching, lengthwise stretching (stretching in the
lengthwise direction of the first substrate), and/or widthwise
stretching. The stretching ratio may be appropriately set within a
range that causes an orientation-controlling force on the surface
of the substrate. When the resin having a positive intrinsic
birefringence is used as the material for the first substrate,
orientation in the stretching direction is given to molecules, and
the slow axis is expressed in the stretching direction.
[0120] The phase difference Re in the in-plane direction of the
first substrate is preferably 30 nm or more, and more preferably 50
nm or more, and is preferably 500 nm or less, and more preferably
300 nm or less. The lower limit of birefringence .DELTA.n of the
first substrate is preferably 0.000050 or more, and more preferably
0.000070 or more. The upper limit of birefringence .DELTA.n of the
first substrate is preferably 0.007500 or less, and more preferably
0.007000 or less. In particular, when the aforementioned resin
containing the alicyclic structure-containing polymer or the resin
containing triacetylcellulose is used as the material for the first
substrate, and optical properties within the range are imparted,
molecular directors can be substantially uniformly oriented over
the entire thickness direction of the first substrate, to impart a
favorable orientation-controlling force to the surface of the first
substrate. The stretching may be performed by any known stretching
machines such as a tenter stretching machine.
[0121] On the other hand, a rubbing treatment can impart an
orientation-controlling force to only the surface layer of the
substrate. Use of an optical orientation film can also impart an
orientation-controlling force to only a thin-film surface layer of
an orientation film layer. The orientation-controlling force
expressed only on the surface layer is alleviated by effects of
environment (heat, light, oxygen, etc.) over time. Thus,
orientation defects may more frequently occur during formation of
the optically anisotropic layer.
[0122] [1.2. Formation of Optically Anisotropic Layer on First
Substrate]
[0123] The multilayer film of the present invention comprises an
optically anisotropic layer that is formed directly on the first
substrate and contains the cured liquid-crystal molecules.
[0124] The formation of the optically anisotropic layer "directly"
on the first substrate means that the optically anisotropic layer
is formed on the surface of the first substrate without another
intervening layer. When the first substrate having an
orientation-controlling force caused by stretching is employed and
the optically anisotropic layer is formed directly on the first
substrate, the optically anisotropic layer having a slow axis in a
desired direction can be obtained without generation of dusts,
generation of defects, nor contamination of a heterogeneous matter
due to rubbing. As a result, an optically anisotropic layer having
a reduced number of defects in orientation can be obtained.
Specifically, the optically anisotropic layer may have a reduced
number of defects and heterogeneous matters that are observed by a
microscope and a reduced number of orientation defects such as line
defects.
[0125] The optically anisotropic layer may typically be formed on
the first substrate by a method including:
[0126] Step (I): a step of feeding out the specific long-length
first substrate described above in the lengthwise direction;
[0127] Step (II): a step of directly applying onto the fed-out
first substrate a liquid crystal composition containing a
polymerizable liquid crystal compound to form a layer of the liquid
crystal composition;
[0128] Step (III): a step of giving orientation to the
polymerizable liquid crystal compound in the layer of the liquid
crystal composition; and
[0129] Step (IV): a step of polymerizing the polymerizable liquid
crystal compound to form cured liquid-crystal molecules.
[0130] Step (I) may be performed by preparing a roll of the
specific long-length first substrate described above, and feeding
out the first substrate from the roll.
[0131] Step (II) may be performed by applying the liquid crystal
composition directly onto one surface of the continuously conveyed
first substrate. The conveyance direction of the substrate may be
usually the same as the applying direction of the liquid crystal
composition. Examples of the applying method may include a curtain
coating method, an extrusion coating method, a roll coating method,
a spin coating method, a dip coating method, a bar coating method,
a spray coating method, a slide coating method, a printing coating
method, a gravure coating method, a die coating method, a gap
coating method, and a dipping method. For example, when a die
coater is disposed in the die coating method so that the lip
direction of the die coater is parallel to the widthwise direction
of the substrate, the applying direction of the liquid crystal
composition is the same as the conveyance direction of the
substrate, that is, the lengthwise direction of the substrate. The
thickness of layer of the liquid crystal composition to be applied
may be appropriately set depending on a desired thickness required
for the optically anisotropic layer.
[0132] Step (III) may be achieved immediately by coating, but if
necessary, be achieved by an orientation treatment such as heating
after coating. Conditions of the orientation treatment may be
appropriately set depending on the properties of the liquid crystal
composition to be used. For example, the conditions may be
conditions of treatment for 30 seconds to 5 minutes under a
temperature condition of 50 to 160.degree. C. When the composition
and treatment conditions of the liquid crystal composition to be
used are appropriately set, orientation in substantially the same
direction as the direction of slow axis of the first substrate can
be achieved. Thereby, the applying direction of the liquid crystal
composition to be used and the orientation direction of the
polymerizable liquid crystal compound may become different, that
is, may intersect. The angle formed between the applying direction
of the liquid crystal composition and the orientation direction of
the polymerizable liquid crystal compound may preferably be more
than 5.degree., more preferably 10 to 90.degree., and further
preferably 40 to 50.degree..
[0133] Step (IV) may be performed immediately after Step (III).
Alternatively, a step of drying the layer of the liquid crystal
composition may be performed, if necessary, before Step (IV) and
after Step (III). The drying may be achieved by a drying method
such as air drying, heated-air drying, drying under reduced
pressure, and heated-air drying under reduced pressure. By the
drying, the solvent can be removed from the layer of the liquid
crystal composition.
[0134] At Step (IV), a method that is suitable for the properties
of components of the liquid crystal composition such as the
polymerizable compound and a polymerization initiator may be
appropriately selected. Examples of the method may include a method
of irradiation with an active energy beam and a thermal
polymerization method. The method of irradiation with an active
energy beam is preferred since a reaction can proceed at room
temperature without heating. Examples of the active energy beam for
irradiation in this method may include light such as visible light,
ultraviolet light, and infrared light, and any energy beam such as
an electron beam. A method of irradiation with light such as
ultraviolet light is particularly preferred because of simple
operation. The upper limit of temperature during irradiation with
ultraviolet light is preferably equal to or lower than the glass
transition temperature (Tg) of the substrate. The upper limit of
temperature usually falls within a range of 150.degree. C. or
lower, preferably 100.degree. C. or lower, and particularly
preferably 80.degree. C. or lower. The lower limit of temperature
during irradiation with ultraviolet light may be 15.degree. C. or
higher. The irradiation intensity of ultraviolet light usually
falls within a range of 0.1 mW/cm.sup.2 to 1,000 mW/cm.sup.2, and
preferably 0.5 mW/cm.sup.2 to 600 mW/cm.sup.2. The irradiation time
of ultraviolet light falls within a range of 1 second to 300
seconds, and preferably 5 seconds to 100 seconds. The integrated
illuminance of ultraviolet light is calculated by the integrated
illuminance of ultraviolet light (mJ/cm.sup.2)=the irradiation
intensity of ultraviolet light (mW/cm.sup.2).times.the irradiation
time of ultraviolet light (second).
[0135] [1.3. Optically Anisotropic Layer]
[0136] In the multilayer film of the present invention, the cured
liquid-crystal molecules may have orientation regularity in
substantially the same direction as the direction of slow axis of
the first substrate.
[0137] The cured liquid-crystal molecules may preferably have
homogeneous orientation regularity in substantially the same
direction as the direction of slow axis of the first substrate.
Herein, "having homogeneous orientation regularity" means that an
average direction of lines that are obtained by projecting
long-axis directions of mesogens of the cured liquid-crystal
molecules to a film face is aligned in a certain direction
horizontal to the film face (for example, direction of surface
director of film of the substrate). Furthermore, the homogeneous
orientation regularity in the certain direction means that the
alignment direction is substantially the same as the certain
direction described above. For example, the certain direction is
the direction of surface director of film of the substrate or the
direction of slow axis of the substrate film. The presence or
absence of homogeneous orientation regularity of the cured
liquid-crystal molecules and the direction of the alignment may be
confirmed by measurement of the slow axis direction using a phase
difference meter typified by AxoScan (manufactured by Axometrics,
Inc.) and measurement of retardation distribution at various
incidence angles in the slow axis direction.
[0138] Herein, when the cured liquid-crystal molecules are obtained
by polymerizing a polymerizable liquid crystal compound having a
rod-like molecular structure, the long-axis direction of mesogen of
the polymerizable liquid crystal compound is usually the long-axis
direction of mesogen of the cured liquid-crystal molecules. When a
plurality of types of mesogens having different orientation
directions exist in the optically anisotropic layer in, e.g., the
instance of using a polymerizable liquid crystal compound having
inverse wavelength distribution (described below) as the
polymerizable liquid crystal compound, a direction in which the
long-axis direction of mesogen of the longest type among them is
aligned is referred to as the alignment direction.
[0139] Further, the orientation in "substantially" the same
direction as the direction of slow axis of the first substrate
means that the angle formed between the direction of slow axis of
the first substrate and the alignment direction of mesogen is
5.degree. or less. The angle is preferably 3.degree. or less, and
more preferably 1.degree. or less.
[0140] When the first substrate having the certain slow axis
described above is used and a material for the optically
anisotropic layer is appropriately selected, orientation regularity
such as homogeneous orientation regularity in substantially the
same direction as the direction of slow axis can be imparted to the
optically anisotropic layer. Therefore, the optically anisotropic
layer having such orientation regularity can be obtained.
[0141] The thickness of the optically anisotropic layer is not
particularly limited, and may be appropriately adjusted so that
properties such as retardation fall within a desired range.
Specifically, the lower limit of the thickness is preferably 0.5
.mu.m or more, and more preferably 1.0 .mu.m or more, whereas the
upper limit of the thickness is preferably 10 .mu.m or less, more
preferably 7 .mu.m or less, and further preferably 5 .mu.m or
less.
[0142] The shape, and length and width of the optically anisotropic
layer may be those of long-length film having the same shape as
that of the first substrate. This optically anisotropic layer may
be cut into a shape such as a rectangle suitable for desired
application, if necessary.
[0143] It is preferable that the optically anisotropic layer has
inverse wavelength distribution. That is, it is preferable that the
optically anisotropic layer has wavelength distribution that
exhibits higher in-plane phase difference for transmitted light
having longer wavelength as compared with transmitted light having
shorter wavelength. It is preferable that the optically anisotropic
layer has inverse wavelength distribution at at least a part or
preferably all of visible light region. When the optically
anisotropic layer has inverse wavelength distribution, the function
can be uniformly expressed over a wide region for optical
applications such as a .lamda./4 wave plate and a .lamda./2 wave
plate.
[0144] In a preferred aspect, the optically anisotropic layer is a
.lamda./4 wave plate or a .lamda./2 wave plate. Specifically, when
the in-plane retardation Re measured at a measurement wavelength of
550 nm falls within a range of 108 nm to 168 nm, the optically
anisotropic layer may be used as a .lamda./4 wave plate. When the
in-plane retardation Re measured at a measurement wavelength of 550
nm falls within a range of 245 nm to 305 nm, the optically
anisotropic layer may be used as a .lamda./2 wave plate. More
specifically, in a case of the .lamda./4 wave plate, the in-plane
retardation Re measured at a measurement wavelength of 550 nm
preferably falls within a range of 128 nm to 148 nm, and more
preferably 133 nm to 143 nm. In a case of the .lamda./2 wave plate,
the in-plane retardation Re measured at a measurement wavelength of
550 nm preferably falls within a range of 265 nm to 285 nm, and
more preferably 270 nm to 280 nm. Herein, the in-plane retardation
Re is calculated by the following equation.
Re=(nx-ny).times.d
(In the equation, nx is a refractive index of the optically
anisotropic layer in an in-plane slow axis direction (maximum
in-plane refractive index), ny is a refractive index of the
optically anisotropic layer in a direction orthogonal to the
in-plane slow axis direction, and d is a thickness of the optically
anisotropic layer (nm).) When the optically anisotropic layer is
such a .lamda./4 wave plate or such a .lamda./2 wave plate, an
optical element such as a circular polarizing plate having the
.lamda./4 wave plate or the .lamda./2 wave plate can be easily
manufactured using the optically anisotropic layer.
[0145] The angle formed between the slow axis of the optically
anisotropic layer and the lengthwise direction of the optically
anisotropic layer may be the same as the angle formed between the
slow axis of the first substrate and the lengthwise direction of
the first substrate. Specifically, the angle formed between the
slow axis of the optically anisotropic layer and the lengthwise
direction of the optically anisotropic layer may be specifically
10.degree. to 90.degree.. In a certain aspect, the angle formed
between the slow axis of the optically anisotropic layer and the
lengthwise direction of the optically anisotropic layer is
particularly preferably 40.degree. to 50.degree.. Specifically, the
angle formed between the slow axis of the optically anisotropic
layer and the lengthwise direction of the optically anisotropic
layer may preferably fall within a specific range of
15.degree..+-.5.degree., 45.degree..+-.5.degree.,
67.5.degree..+-.5.degree., or 75.degree..+-.5.degree., more
preferably 15.degree..+-.4.degree., 45.degree..+-.4.degree.,
67.5.degree..+-.4.degree., or 75.degree..+-.4.degree., and further
preferably 15.degree..+-.3.degree., 45.degree..+-.3.degree.,
67.5.degree..+-.3.degree., or 75.degree..+-.3.degree.. When this
angle relationship is satisfied, the multilayer film of the present
invention may serve as a material capable of efficiently
manufacturing a specific circular polarizing plate.
[0146] [1.4. Liquid Crystal Composition]
[0147] The liquid crystal composition containing the polymerizable
liquid crystal compound that may be used for manufacturing of the
multilayer film of the present invention (hereinafter the
composition is sometimes abbreviated as "composition (A)") will be
described.
[0148] The liquid crystal compound as a component of the
composition (A) herein is a compound capable of exhibiting a liquid
crystal phase when the compound is mixed in the composition (A) and
oriented. The polymerizable liquid crystal compound is a liquid
crystal compound that is capable of being polymerized while keeping
a state of the liquid crystal phase in the composition (A) to form
a polymer in which the orientation of molecules in the liquid
crystal phase is maintained. Further, the polymerizable liquid
crystal compound having inverse wavelength distribution is a
polymerizable liquid crystal compound in which a polymer obtained
as described above exhibits inverse wavelength distribution.
[0149] In this application, compounds having polymerizability (the
polymerizable liquid crystal compound, other compounds having
polymerizability, etc.) as the component of the composition (A) are
sometimes collectively referred to as "polymerizable compound".
[0150] [1.4.1. Polymerizable Liquid Crystal Compound]
[0151] Examples of the polymerizable liquid crystal compound may
include a liquid crystal compound having a polymerizable group, a
compound capable of forming a side chain-type liquid crystal
polymer, and a discotic liquid crystal compound. Examples of the
liquid crystal compound having a polymerizable group may include
rod-like liquid crystal compounds having a polymerizable group
described in Japanese Patent Application Laid-Open Nos. Hei.
11-513360 A, 2002-030042 A, 2004-204190 A, 2005-263789 A,
2007-119415 A, and 2007-186430 A. Examples of the side chain-type
liquid crystal polymer compound may include a side chain-type
liquid crystal polymer compound described in Japanese Patent
Application Laid-Open No. 2003-177242 A. Examples of product name
of preferred liquid crystal compound may include "LC242" available
from BASF. Specific examples of the discotic liquid crystal
compound are described in Japanese Patent Application Laid-Open No.
Hei. 8-50206 A, and documents (C. Destrade et al., Mol. Crysr. Liq.
Cryst., vol. 71, page 111 (1981); Edited by the Chemical Society of
Japan, Kikan Kagaku Sosetsu, No. 22, Ekisho-no-kagaku (Chemistry of
Liquid Crystal), Chapter 5, Chapter 10 Section 2 (1994); B. Kohne
et al., Angew. Chem. Soc. Chem. Comm., page 1794 (1985); and J.
Zhang et al., J. Am. Chem. Soc., vol. 116, page 2655 (1994)). One
type of each of these liquid crystal compound and polymerizable
liquid crystal compound having inverse wavelength distribution
described below may be used alone or two or more types thereof may
be used in combination at any ratio.
[0152] [1.4.2. Polymerizable Liquid Crystal Compound having Inverse
Wavelength Distribution]
[0153] As a part or all of the polymerizable liquid crystal
compound, the polymerizable liquid crystal compound having inverse
wavelength distribution may be used. When the polymerizable liquid
crystal compound having inverse wavelength distribution is used, an
optically anisotropic layer having inverse wavelength distribution
can be easily obtained.
[0154] Examples of the polymerizable liquid crystal compound having
inverse wavelength distribution may include a compound having in
the molecule a main chain mesogen and a side chain mesogen bonded
to the main chain mesogen. In a state where the polymerizable
liquid crystal compound having inverse wavelength distribution is
oriented, the side chain mesogen may be oriented in a direction
different from that of the main chain mesogen. Therefore, the main
chain mesogen and the side chain mesogen may be oriented in
different directions in the optically anisotropic layer. By virtue
of this orientation, the optically anisotropic layer may exhibit
inverse wavelength distribution.
[0155] [1.4.2.1. Compound (I)]
[0156] Examples of the polymerizable liquid crystal compound having
inverse wavelength distribution may include a compound represented
by the following formula (I) (hereinafter sometimes referred to as
"compound (I)").
##STR00001##
[0157] When the polymerizable liquid crystal compound having
inverse wavelength distribution is the compound (I), a
--Y.sup.5-A.sup.4-Y.sup.3-A.sup.2-Y.sup.1-A.sup.1-Y.sup.2-A.sup.3-Y.sup.4-
-A.sup.5-Y.sup.6-- group is the main chain mesogen, and a
>A.sup.1-C(Q.sup.1)=N--N(A.sup.x)A.sup.y group is the side chain
mesogen. The A.sup.1 group affects both properties of the main
chain mesogen and the side chain mesogen.
[0158] In the formula, Y.sup.1 to Y.sup.8 are each independently a
chemical single bond, --O--, --S--, --O--C(.dbd.O)--,
--C(.dbd.O)--O--, --O--C(.dbd.O)--O--, --NR.sup.1--C(.dbd.O)--,
--C(.dbd.O)--NR.sup.1--, --O--C(.dbd.O)--NR.sup.1--,
--NR.sup.1--C(.dbd.O)--O--, --NR.sup.1--C(.dbd.O)--NR.sup.1--,
--O--NR.sup.1--, or --NR.sup.1--O--.
[0159] Herein, R.sup.1 represents a hydrogen atom or an alkyl group
having 1 to 6 carbon atoms.
[0160] Examples of the alkyl group having 1 to 6 carbon atoms of
R.sup.1 may include a methyl group, an ethyl group, a n-propyl
group, an isopropyl group, a n-butyl group, a sec-butyl group, a
tert-butyl group, a n-pentyl group, and a n-hexyl group.
[0161] It is preferable that R.sup.1 is a hydrogen atom or an alkyl
group having 1 to 4 carbon atoms.
[0162] In the compound (I), it is preferable that Y to Y.sup.8 are
each independently a chemical single bond, --O--, --O--C(.dbd.O)--,
--C(.dbd.O)--O--, or --O--C(.dbd.O)--O--.
[0163] G.sup.1 and G.sup.2 are each independently a divalent
aliphatic group optionally having a substituent and having 1 to 20
carbon atoms.
[0164] Examples of the divalent aliphatic group having 1 to 20
carbon atoms may include a divalent aliphatic group having a linear
structure such as an alkylene group having 1 to 20 carbon atoms and
an alkenylene group having 2 to 20 carbon atoms; and a divalent
aliphatic group such as a cycloalkanediyl group having 3 to 20
carbon atoms, a cycloalkenediyl group having 4 to 20 carbon atoms,
and a divalent alicyclic fused ring group having 10 to 30 carbon
atoms.
[0165] Examples of the substituent in the divalent aliphatic groups
of G.sup.1 and G.sup.2 may include a halogen atom such as a
fluorine atom, a chlorine atom, a bromine atom, and an iodine atom;
and an alkoxy group having 1 to 6 carbon atoms such as a methoxy
group, an ethoxy group, a n-propoxy group, an isopropoxy group, a
n-butoxy group, a sec-butoxy group, a tert-butoxy group, a
n-pentyloxy group, and a n-hexyloxy group. Among these, a fluorine
atom, a methoxy group, and an ethoxy group are preferred.
[0166] The aforementioned aliphatic groups may have --O--, --S--,
--O--C(.dbd.O)--, --C(.dbd.O)--O--, --O--C(.dbd.O)--O--,
--NR.sup.2--C(.dbd.O)--, --C(.dbd.O)--NR.sup.2--, --NR.sup.2--, or
--C(.dbd.O)-- inserted therein, with a proviso that cases where two
or more --O-- or --S-- groups are adjacently inserted are excluded.
Herein, R.sup.2 represents a hydrogen atom or an alkyl group having
1 to 6 carbon atoms, that are the same as those for R.sup.1
described above. It is preferable that R.sup.2 is a hydrogen atom
or a methyl group.
[0167] It is preferable that the group inserted into the aliphatic
groups is --O--, --O--C(.dbd.O)--, --C(.dbd.O)--O--, or
--C(.dbd.O)--.
[0168] Specific examples of the aliphatic groups into which the
groups are inserted may include
--CH.sub.2--CH.sub.2--O--CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--S--CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--O--C(.dbd.O)--CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--C(.dbd.O) --O--CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--C(.dbd.O)--O--CH.sub.2--,
--CH.sub.2--O--C(.dbd.O)--O--CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--NR.sup.2--C(.dbd.O)--CH.sub.2--CH.sub.2--,
--CH.sub.2--CH.sub.2--C(.dbd.O)--NR.sup.2--CH.sub.2--,
--CH.sub.2--NR.sup.2--CH.sub.2--CH.sub.2--, and
--CH.sub.2--C(.dbd.O)--CH.sub.2--.
[0169] Among these, from the viewpoint of obtaining the desired
effect of the present invention in more favorable manner, it is
preferable that G.sup.1 and G.sup.2 are each independently a
divalent aliphatic group having a linear structure such as an
alkylene group having 1 to 20 carbon atoms and an alkenylene group
having 2 to 20 carbon atoms, more preferably an alkylene group
having 1 to 12 carbon atoms such as a methylene group, an ethylene
group, a trimethylene group, a propylene group, a tetramethylene
group, a pentamethylene group, a hexamethylene group, an
octamethylene group, and a decamethylene group
[--(CH.sub.2).sub.10--], and particularly preferably a
tetramethylene group [--(CH.sub.2).sub.4--], a hexamethylene group
[--(CH.sub.2).sub.6--], an octamethylene group
[--(CH.sub.2).sub.8--], or a decamethylene group
[--(CH.sub.2).sub.10--].
[0170] Z.sup.1 and Z.sup.2 are each independently an alkenyl group
having 2 to 10 carbon atoms that is unsubstituted or substituted by
a halogen atom.
[0171] It is preferable that the number of carbon atoms in the
alkenyl group is 2 to 6. Examples of the halogen atom that is a
substituent in the alkenyl groups of Z.sup.1 and Z.sup.2 may
include a fluorine atom, a chlorine atom, and a bromine atom. It is
preferable that the halogen is a chlorine atom.
[0172] Specific examples of the alkenyl groups having 2 to 10
carbon atoms of Z.sup.1 and Z.sup.2 may include CH.sub.2.dbd.CH--,
CH.sub.2.dbd.C (CH.sub.3)--, CH.sub.2.dbd.CH--CH.sub.2--,
CH.sub.3--CH.dbd.CH--, CH.sub.2.dbd.CH--CH.sub.2--CH.sub.2--,
CH.sub.2.dbd.C(CH.sub.3)--CH.sub.2--CH.sub.2--,
(CH.sub.3).sub.2C.dbd.CH--CH.sub.2--,
(CH.sub.3).sub.2C.dbd.CH--CH.sub.2--CH.sub.2--,
CH.sub.2.dbd.C(Cl)--, CH.sub.2.dbd.C(CH.sub.3)--CH.sub.2--, and
CH.sub.3--CH.dbd.CH--CH.sub.2--.
[0173] Among these, from the viewpoint of obtaining the desired
effect of the present invention in more favorable manner, it is
preferable that Z.sup.1 and Z.sup.2 are each independently
CH.sub.2.dbd.CH--, CH.sub.2.dbd.C(CH.sub.3)--,
CH.sub.2.dbd.C(Cl)--, CH.sub.2.dbd.CH--CH.sub.2--,
CH.sub.2.dbd.C(CH.sub.3)--CH.sub.2--, or
CH.sub.2.dbd.C(CH.sub.3)--CH.sub.2--CH.sub.2--, more preferably
CH.sub.2.dbd.CH--, CH.sub.2.dbd.C(CH.sub.3)-- or CH.sub.2.dbd.C(Cl
)--, and particularly preferably CH.sub.2.dbd.CH--.
[0174] A.sup.x is an organic group having 2 to 30 carbon atoms that
has at least one aromatic ring selected from the group consisting
of an aromatic hydrocarbon ring and an aromatic heterocyclic
ring.
[0175] In the present invention, "aromatic ring" means a cyclic
structure having aromaticity in the broad sense based on Huckel
rule, that is, a cyclic conjugated structure having (4n+2) .pi.
electrons, and a structure that exhibits aromaticity by involving a
lone pair of heteroatom such as sulfur, oxygen, and nitrogen in a
.pi. electron system, typified by thiophene, furan, and
benzothiazole.
[0176] The organic group having 2 to 30 carbon atoms that has at
least one aromatic ring selected from the group consisting of an
aromatic hydrocarbon ring and an aromatic heterocyclic ring, of
A.sup.x, may have a plurality of aromatic rings, or have an
aromatic hydrocarbon ring and an aromatic heterocyclic ring.
[0177] Examples of the aromatic hydrocarbon ring may include a
benzene ring, a naphthalene ring, and an anthracene ring. Examples
of the aromatic heterocyclic ring may include a monocyclic aromatic
heterocyclic ring such as a pyrrole ring, a furan ring, a thiophene
ring, a pyridine ring, a pyridazine ring, a pyrimidine ring, a
pyrazine ring, a pyrazole ring, an imidazole ring, an oxazole ring,
and a thiazole ring; and a fused aromatic heterocyclic ring such as
a benzothiazole ring, a benzoxazole ring, a quinoline ring, a
phthalazine ring, a benzimidazole ring, a benzopyrazole ring, a
benzofuran ring, a benzothiophene ring, a thiazolopyridine ring, an
oxazolopyridine ring, a thiazolopyrazine ring, an oxazolopyrazine
ring, a thiazolopyridazine ring, an oxazolopyridazine ring, a
thiazolopyrimidine ring, and an oxazolopyrimidine ring.
[0178] The aromatic ring of A.sup.x may have a substituent.
Examples of the substituent may include a halogen atom such as a
fluorine atom and a chlorine atom; a cyano group; an alkyl group
having 1 to 6 carbon atoms such as a methyl group, an ethyl group,
and a propyl group; an alkenyl group having 2 to 6 carbon atoms
such as a vinyl group and an allyl group; a halogenated alkyl group
having 1 to 6 carbon atoms such as a trifluoromethyl group; a
substituted amino group such as a dimethylamino group; an alkoxy
group having 1 to 6 carbon atoms such as a methoxy group, an ethoxy
group, and an isopropoxy group; a nitro group; an aryl group such
as a phenyl group and a naphthyl group; --C(.dbd.O)--R.sup.5;
--C(.dbd.O)--OR.sup.3; and --SO.sub.2R.sup.6. Herein, R.sup.5 is an
alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2
to 20 carbon atoms, or a cycloalkyl group having 3 to 12 carbon
atoms, and R.sup.6 is an alkyl group having 1 to 20 carbon atoms,
an alkenyl group having 2 to 20 carbon atoms, a phenyl group, or a
4-methylphenyl group, that are the same as those for R.sup.4
described below.
[0179] The aromatic ring of A.sup.x may have a plurality of
substituents that may be the same or different, and two adjacent
substituents may be bonded together to form a ring. The formed ring
may be a monocycle or a fused polycycle, and may be an unsaturated
ring or a saturated ring.
[0180] The "number of carbon atoms" in the organic group having 2
to 30 carbon atoms of A.sup.x means the total number of carbon
atoms in the entire organic group which excludes carbon atoms in
the substituents (the same applies to A.sup.y described below).
[0181] Examples of the organic group having 2 to 30 carbon atoms
that has at least one aromatic ring selected from the group
consisting of an aromatic hydrocarbon ring and an aromatic
heterocyclic ring of A.sup.x may include an aromatic hydrocarbon
ring group; an aromatic heterocyclic ring group; an alkyl group
having 3 to 30 carbon atoms that has at least one aromatic ring
selected from the group consisting of an aromatic hydrocarbon ring
group and an aromatic heterocyclic ring group; an alkenyl group
having 4 to 30 carbon atoms that has at least one aromatic ring
selected from the group consisting of an aromatic hydrocarbon ring
group and an aromatic heterocyclic ring group; and an alkynyl group
having 4 to 30 carbon atoms that has at least one aromatic ring
selected from the group consisting of an aromatic hydrocarbon ring
group and an aromatic heterocyclic ring group.
[0182] Preferable ones of specific examples of A.sup.x are as
follows. However, in the present invention, A.sup.x is not limited
to the following examples. In the following formulae, "--"
represents an atomic bonding at any position of the ring (the same
applies to the following).
[0183] (1) An Aromatic Hydrocarbon Ring Group
##STR00002##
[0184] (2) An Aromatic Heterocyclic Ring Group
##STR00003##
[0185] In the aforementioned formulae, E is NR.sup.6a, an oxygen
atom, or a sulfur atom. Herein, R.sup.6a is a hydrogen atom; or an
alkyl group having 1 to 6 carbon atoms such as a methyl group, an
ethyl group, and a propyl group.
##STR00004##
[0186] In the aforementioned formulae, X, Y, and Z are each
independently NR.sup.7, an oxygen atom, a sulfur atom, --SO--, or
--SO.sub.2-- (provided that cases where an oxygen atom, a sulfur
atom, --SO--, and --SO.sub.2-- are each adjacent are excluded).
R.sup.7 is a hydrogen atom; or an alkyl group having 1 to 6 carbon
atoms such as a methyl group, an ethyl group, and a propyl group,
that are the same as those for R.sup.6a described above.
##STR00005##
[0187] (In the aforementioned formulae, X has the same meanings as
described above.)
[0188] (3) An alkyl Group Having at Least One Aromatic Ring
Selected from the Group Consisting of an Aromatic Hydrocarbon Ring
Group and an Aromatic Heterocyclic Ring Group
##STR00006##
[0189] (4) An Alkenyl Group Having at Least One Aromatic Ring
Selected from the Group Consisting of an Aromatic Hydrocarbon Ring
Group and an Aromatic Heterocyclic Ring Group
##STR00007##
[0190] (5) An Alkynyl Group Having at Least One Aromatic Ring
Selected from the Group Consisting of an Aromatic Hydrocarbon Ring
Group and an Aromatic Heterocyclic Ring Group
##STR00008##
[0191] Among the groups of A.sup.x, an aromatic hydrocarbon group
having 6 to 30 carbon atoms and an aromatic heterocyclic ring group
having 4 to 30 carbon atoms are preferred. Any of the groups shown
below are more preferred.
##STR00009##
[0192] Any of the groups shown below is further preferred.
##STR00010##
[0193] The ring of A.sup.x may have a substituent. Examples of the
substituent may include a halogen atom such as a fluorine atom and
a chlorine atom; a cyano group; an alkyl group having 1 to 6 carbon
atoms such as a methyl group, an ethyl group, and a propyl group;
an alkenyl group having 2 to 6 carbon atoms such as a vinyl group
and an allyl group; a halogenated alkyl group having 1 to 6 carbon
atoms such as a trifluoromethyl group; a substituted amino group
such as a dimethylamino group; an alkoxy group having 1 to 6 carbon
atoms such as a methoxy group, an ethoxy group, and an isopropyl
group; a nitro group; an aryl group such as a phenyl group and a
naphthyl group; --C(.dbd.O)--R.sup.8; --C(.dbd.O)--OR.sup.8; and
--SO.sub.2R.sup.6. Herein, R.sup.8 is an alkyl group having 1 to 6
carbon atoms such as a methyl group and an ethyl group; or an aryl
group having 6 to 14 carbon atoms such as a phenyl group. Among
these, a halogen atom, a cyano group, an alkyl group having 1 to 6
carbon atoms, and an alkoxy group having 1 to 6 carbon atoms are
preferred.
[0194] The ring of A.sup.x may have a plurality of substituents
that are the same or different, and two adjacent substituents may
be bonded together to form a ring. The formed ring may be a
monocycle or a fused polycycle.
[0195] The "number of carbon atoms" in the organic group having 2
to 30 carbon atoms of A.sup.x means the total number of carbon
atoms in the entire organic group which excludes carbon atoms in
the substituents (the same applies to A.sup.y described below).
[0196] A.sup.y is a hydrogen atom, an alkyl group having 1 to 20
carbon atoms and optionally having a substituent, an alkenyl group
having 2 to 20 carbon atoms and optionally having a substituent, a
cycloalkyl group having 3 to 12 carbon atoms and optionally having
a substituent, an alkynyl group having 2 to 20 carbon atoms and
optionally having a substituent, --C(.dbd.O)--R.sup.3,
--SO.sub.2--R.sup.4, --C(.dbd.S)NH--R.sup.9, or an organic group
having 2 to 30 carbon atoms that has at least one aromatic ring
selected from the group consisting of an aromatic hydrocarbon ring
and an aromatic heterocyclic ring. Herein, R.sup.3 is an alkyl
group having 1 to 20 carbon atoms and optionally having a
substituent, an alkenyl group having 2 to 20 carbon atoms and
optionally having a substituent, a cycloalkyl group having 3 to 12
carbon atoms and optionally having a substituent, or an aromatic
hydrocarbon group having 5 to 12 carbon atoms, R.sup.4 is an alkyl
group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20
carbon atoms, a phenyl group, or a 4-methylphenyl group, and
R.sup.9 is an alkyl group having 1 to 20 carbon atoms and
optionally having a substituent, an alkenyl group having 2 to 20
carbon atoms and optionally having a substituent, a cycloalkyl
group having 3 to 12 carbon atoms and optionally having a
substituent, or an aromatic group having 5 to 20 carbon atoms and
optionally having a substituent.
[0197] Examples of the alkyl group having 1 to 20 carbon atoms in
the alkyl group having 1 to 20 carbon atoms and optionally having a
substituent of A.sup.y may include a methyl group, an ethyl group,
a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl
group, a 1-methylpentyl group, a 1-ethylpentyl group, a sec-butyl
group, a tert-butyl group, a n-pentyl group, an isopentyl group, a
neopentyl group, a n-hexyl group, an isohexyl group, a n-heptyl
group, a n-octyl group, a n-nonyl group, a n-decyl group, a
n-undecyl group, a n-dodecyl group, a n-tridecyl group, a
n-tetradecyl group, a n-pentadecyl group, a n-hexadecyl group, a
n-heptadecyl group, a n-octadecyl group, a n-nonadecyl group, and a
n-icosyl group. The number of carbon atoms in the alkyl group
having 1 to 20 carbon atoms and optionally having a substituent is
preferably 1 to 12, and further preferably 4 to 10.
[0198] Examples of the alkenyl group having 2 to 20 carbon atoms in
the alkenyl group having 2 to 20 carbon atoms and optionally having
a substituent of A.sup.y may include a vinyl group, a propenyl
group, an isopropenyl group, a butenyl group, an isobutenyl group,
a pentenyl group, a hexenyl group, a heptenyl group, an octenyl
group, a decenyl group, an undecenyl group, a dodecenyl group, a
tridecenyl group, a tetradecenyl group, a pentadecenyl group, a
hexadecenyl group, a heptadecenyl group, an octadecenyl group, a
nonadecenyl group, and an icocenyl group.
[0199] The number of carbon atoms in the alkenyl group having 2 to
20 carbon atoms and optionally having a substituent is preferably 2
to 12.
[0200] Examples of the cycloalkyl group having 3 to 12 carbon atoms
in the cycloalkyl group having 3 to 12 carbon atoms and optionally
having a substituent of A.sup.y may include a cyclopropyl group, a
cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a
cyclooctyl group.
[0201] Examples of the alkynyl group having 2 to 20 carbon atoms in
the alkynyl group having 2 to 20 carbon atoms and optionally having
a substituent of A.sup.y may include an ethynyl group, a propynyl
group, a 2-propynyl group (propargyl group), a butynyl group, a
2-butynyl group, a 3-butynyl group, a pentynyl group, a 2-pentynyl
group, a hexynyl group, a 5-hexynyl group, a heptynyl group, an
octynyl group, a 2-octynyl group, a nonanyl group, a decanyl group,
and a 7-decanyl group.
[0202] Examples of the substituents in the alkyl group having 1 to
20 carbon atoms and optionally having a substituent and the alkenyl
group having 2 to 20 carbon atoms and optionally having a
substituent, of A.sup.y, may include a halogen atom such as a
fluorine atom and a chlorine atom; a cyano group; a substituted
amino group such as a dimethylamino group; an alkoxy group having 1
to 20 carbon atoms such as a methoxy group, an ethoxy group, an
isopropyl group, and a butoxy group; an alkoxy group having 1 to 12
carbon atoms that is substituted by an alkoxy group having 1 to 12
carbon atoms such as a methoxymethoxy group and a methoxyethoxy
group; a nitro group; an aryl group such as a phenyl group and a
naphthyl group; a cycloalkyl group having 3 to 8 carbon atoms such
as a cyclopropyl group, a cyclopentyl group, and a cyclohexyl
group; a cycloalkyloxy group having 3 to 8 carbon atoms such as a
cyclopentyloxy group and a cyclohexyloxy group; a cyclic ether
group having 2 to 12 carbon atoms such as a tetrahydrofuranyl
group, a tetrahydropyranyl group, a dioxolanyl group, and a
dioxanyl group; an aryloxy group having 6 to 14 carbon atoms such
as a phenoxy group and a naphthoxy group; a fluoroalkoxy group
having 1 to 12 carbon atoms with at least one substitution by a
fluoro atom, such as a trifluoromethyl group, a pentafluoroethyl
group, and --CH.sub.2CF.sub.3; a benzofuryl group; a benzopyranyl
group; a benzodioxolyl group; a benzodioxanyl group;
--C(.dbd.O)--R.sup.7a; --C(.dbd.O)--OR.sup.7a; --SO.sub.2R.sup.8a;
--SR.sup.10; an alkoxy group having 1 to 12 carbon atoms that is
substituted by --SR.sup.10; and a hydroxyl group. Herein, R.sup.7a
and R.sup.10 are each independently an alkyl group having 1 to 20
carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a
cycloalkyl group having 3 to 12 carbon atoms, or an aromatic
hydrocarbon group having 6 to 12 carbon atoms, and R.sup.8a is an
alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2
to 20 carbon atoms, a phenyl group, or a 4-methylphenyl group, that
are the same as those for R.sup.4 described above.
[0203] Examples of the substituent in the cycloalkyl group having 3
to 12 carbon atoms and optionally having a substituent of A.sup.y
may include a halogen atom such as a fluorine atom and a chlorine
atom; a cyano group; a substituted amino group such as a
dimethylamino group; an alkyl group having 1 to 6 carbon atoms such
as a methyl group, an ethyl group, and a propyl group; an alkoxy
group having 1 to 6 carbon atoms such as a methoxy group, an ethoxy
group, and an isopropyl group; a nitro group; an aryl group such as
a phenyl group and a naphthyl group; a cycloalkyl group having 3 to
8 carbon atoms such as a cyclopropyl group, a cyclopentyl group,
and a cyclohexyl group; --C(.dbd.O)--R.sup.7a;
--C(.dbd.O)--OR.sup.7a; --SO.sub.2R.sup.8a; and a hydroxyl group.
Herein, R.sup.7a and R.sup.8a have the same meanings as described
above.
[0204] Examples of the substituent in the alkynyl group having 2 to
20 carbon atoms and optionally having a substituent of A.sup.y may
include substituents that are the same as the substituents in the
alkyl group having 1 to 20 carbon atoms and optionally having a
substituent and the alkenyl group having 2 to 20 carbon atoms and
optionally having a substituent.
[0205] In the group represented by --C(.dbd.O)--R.sup.3 of A.sup.y,
R.sup.3 is an alkyl group having 1 to 20 carbon atoms and
optionally having a substituent, an alkenyl group having 2 to 20
carbon atoms and optionally having a substituent, a cycloalkyl
group having 3 to 12 carbon atoms and optionally having a
substituent, or an aromatic hydrocarbon group having 5 to 12 carbon
atoms. Specific examples thereof may include those exemplified as
the examples of the alkyl group having 1 to 20 carbon atoms and
optionally having a substituent, the alkenyl group having 2 to 20
carbon atoms and optionally having a substituent, and the
cycloalkyl group having 3 to 12 carbon atoms and optionally having
a substituent, of A.sup.y described above.
[0206] In the group represented by --SO.sub.2--R.sup.4 of A.sup.y,
R.sup.4 is an alkyl group having 1 to 20 carbon atoms, an alkenyl
group having 2 to 20 carbon atoms, a phenyl group, or a
4-methylphenyl group.
[0207] Specific examples of the alkyl group having 1 to 20 carbon
atoms and the alkenyl group having 2 to 20 carbon atoms, of
R.sup.4, may include those exemplified as the examples of the alkyl
group having 1 to 20 carbon atoms and the alkenyl group having 2 to
20 carbon atoms, of A.sup.y described above.
[0208] Examples of the organic group having 2 to 30 carbon atoms
that has at least one aromatic ring selected from the group
consisting of an aromatic hydrocarbon ring and an aromatic
heterocyclic ring of A.sup.y may include those exemplified as the
examples of A.sup.x described above.
[0209] Among these, it is preferable that A.sup.y is a hydrogen
atom, an alkyl group having 1 to 20 carbon atoms and optionally
having a substituent, an alkenyl group having 2 to 20 carbon atoms
and optionally having a substituent, a cycloalkyl group having 3 to
12 carbon atoms and optionally having a substituent, an alkynyl
group having 2 to 20 carbon atoms and optionally having a
substituent, --C(.dbd.O)--13 R.sup.3, --SO.sub.2--R.sup.4, or an
organic group having 2 to 30 carbon atoms that has at least one
aromatic ring selected from the group consisting of an aromatic
hydrocarbon ring and an aromatic heterocyclic ring, and further
preferably a hydrogen atom, an alkyl group having 1 to 20 carbon
atoms and optionally having a substituent, an alkenyl group having
2 to 20 carbon atoms and optionally having a substituent, a
cycloalkyl group having 3 to 12 carbon atoms and optionally having
a substituent, an alkynyl group having 2 to 20 carbon atoms and
optionally having a substituent, an aromatic hydrocarbon group
having 6 to 12 carbon atoms and optionally having a substituent, an
aromatic heterocyclic ring group having 3 to 9 carbon atoms and
optionally having a substituent, or a group represented by
--C(.dbd.O)--R.sup.3 or --SO.sub.2--R.sup.4. Herein, R.sup.3 and
R.sup.4 have the same meanings as described above.
[0210] It is preferable that substituents in the alkyl group having
1 to 20 carbon atoms and optionally having a substituent, the
alkenyl group having 2 to 20 carbon atoms and optionally having a
substituent, and the alkynyl group having 2 to 20 carbon atoms and
optionally having a substituent, of A.sup.y are a halogen atom, a
cyano group, an alkoxy group having 1 to 20 carbon atoms, an alkoxy
group having 1 to 12 carbon atoms that is substituted by an alkoxy
group having 1 to 12 carbon atoms, a phenyl group, a cyclohexyl
group, a cyclic ether group having 2 to 12 carbon atoms, an aryloxy
group having 6 to 14 carbon atoms, a hydroxyl group, a
benzodioxanyl group, a phenylsulfonyl group, a
4-methylphenylsulfonyl group, a benzoyl group, or --SR.sup.10.
Herein, R.sup.10 has the same meanings as described above.
[0211] It is preferable that substituents in the cycloalkyl group
having 3 to 12 carbon atoms and optionally having a substituent,
the aromatic hydrocarbon group having 6 to 12 carbon atoms and
optionally having a substituent, and the aromatic heterocyclic
group having 3 to 9 carbon atoms and optionally having a
substituent, of A.sup.y are a fluorine atom, an alkyl group having
1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or
a cyano group.
[0212] A.sup.x and A.sup.y may together form a ring. Examples of
the ring may include an unsaturated heterocyclic ring having 4 to
30 carbon atoms and an unsaturated carbon ring having 6 to 30
carbon atoms which may optionally have a substituent.
[0213] The aforementioned unsaturated heterocyclic ring having 4 to
30 carbon atoms and the aforementioned unsaturated carbon ring
having 6 to 30 carbon atoms are not particularly restricted, and
may or may not have aromaticity. Examples thereof may include rings
shown below. The rings shown below are a moiety of:
##STR00011##
[0214] in the formula (I).
##STR00012## ##STR00013## ##STR00014##
[0215] (In the formulae, X, Y, and Z have the same meanings as
described above.)
[0216] The rings may have a substituent. Examples of the
substituent may include those exemplified as the examples of the
substituent in the aromatic ring of A.sup.x.
[0217] The total number of .pi. electrons in A.sup.x and A.sup.y is
preferably 4 or more and 24 or less, more preferably 6 or more and
20 or less, and further preferably 6 or more and 18 or less from
the viewpoint of obtaining the desired effect of the present
invention in more favorable manner.
[0218] Examples of preferred combination of A.sup.x and A.sup.y may
include:
[0219] (.alpha.) a combination of A.sup.x and A.sup.y in which
A.sup.x is an aromatic hydrocarbon group having 4 to 30 carbon
atoms or an aromatic heterocyclic ring group having 4 to 30 carbon
atoms, A.sup.y is a hydrogen atom, a cycloalkyl group having 3 to 8
carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon
atoms and optionally having a substituent group (a halogen atom, a
cyano group, an alkyl group having 1 to 6 carbon atoms, an alkoxy
group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to
8 carbon atoms), an aromatic heterocyclic ring group having 3 to 9
carbon atoms and optionally having a substituent (a halogen atom,
an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1
to 6 carbon atoms, or a cyano group), an alkyl group having 1 to 20
carbon atoms and optionally having a substituent, an alkenyl group
having 1 to 20 carbon atoms and optionally having a substituent, or
an alkynyl group having 2 to 20 carbon atoms and optionally having
a substituent, and the substituent is any of a halogen atom, a
cyano group, an alkoxy group having 1 to 20 carbon atoms, an alkoxy
group having 1 to 12 carbon atoms that is substituted by an alkoxy
group having 1 to 12 carbon atoms, a phenyl group, a cyclohexyl
group, a cyclic ether group having 2 to 12 carbon atoms, an aryloxy
group having 6 to 14 carbon atoms, a hydroxyl group, a
benzodioxanyl group, a benzenesulfonyl group, a benzoyl group, and
--SR.sup.10; and
[0220] (.beta.) a combination of A.sup.x and A.sup.y in which
A.sup.x and A.sup.y together form an unsaturated heterocyclic ring
or an unsaturated carbon ring. Herein, R.sup.10 has the same
meanings as described above.
[0221] Examples of further preferred combination of A.sup.x and
A.sup.y may include
[0222] (.gamma.) a combination of A.sup.x and A.sup.y in which
A.sup.x is any of groups having the following structures, A.sup.y
is a hydrogen atom, a cycloalkyl group having 3 to 8 carbon atoms,
an aromatic hydrocarbon group having 6 to 12 carbon atoms and
optionally having a substituent (a halogen atom, a cyano group, an
alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to
6 carbon atoms, or a cycloalkyl group having 3 to 8 carbon atoms),
an aromatic heterocyclic ring group having 3 to 9 carbon atoms and
optionally having a substituent (a halogen atom, an alkyl group
having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon
atoms, or a cyano group), an alkyl group having 1 to 20 carbon
atoms and optionally having a substituent, an alkenyl group having
1 to 20 carbon atoms and optionally having a substituent, or an
alkynyl group having 2 to 20 carbon atoms and optionally having a
substituent, and the substituent is any of a halogen atom, a cyano
group, an alkoxy group having 1 to 20 carbon atoms, an alkoxy group
having 1 to 12 carbon atoms that is substituted by an alkoxy group
having 1 to 12 carbon atoms, a phenyl group, a cyclohexyl group, a
cyclic ether group having 2 to 12 carbon atoms, an aryloxy group
having 6 to 14 carbon atoms, a hydroxyl group, a benzodioxanyl
group, a benzenesulfonyl group, a benzoyl group, and --SR.sup.10.
Herein, R.sup.10 has the same meanings as described above.
##STR00015##
[0223] (In the formulae, X and Y have the same meanings as
described above.)
[0224] Examples of particularly preferred combination of A.sup.x
and A.sup.y may include
[0225] (.delta.) a combination of A.sup.x and A.sup.y in which
A.sup.x is any of groups having the following structures, A.sup.y
is a hydrogen atom, a cycloalkyl group having 3 to 8 carbon atoms,
an aromatic hydrocarbon group having 6 to 12 carbon atoms and
optionally having a substituent (a halogen atom, a cyano group, an
alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to
6 carbon atoms, or a cycloalkyl group having 3 to 8 carbon atoms),
an aromatic heterocyclic ring group having 3 to 9 carbon atoms and
optionally having a substituent (a halogen atom, an alkyl group
having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon
atoms, or a cyano group), an alkyl group having 1 to 20 carbon
atoms and optionally having a substituent, an alkenyl group having
1 to 20 carbon atoms and optionally having a substituent, or an
alkynyl group having 2 to 20 carbon atoms and optionally having a
substituent, and the substituent is any of a halogen atom, a cyano
group, an alkoxy group having 1 to 20 carbon atoms, an alkoxy group
having 1 to 12 carbon atoms that is substituted by an alkoxy group
having 1 to 12 carbon atoms, a phenyl group, a cyclohexyl group, a
cyclic ether group having 2 to 12 carbon atoms, an aryloxy group
having 6 to 14 carbon atoms, a hydroxyl group, a benzodioxanyl
group, a benzenesulfonyl group, a benzoyl group, and --SR.sup.10.
In the following formulae, X has the same meanings as described
above. Herein, R.sup.10 has the same meanings as described
above.
##STR00016##
[0226] A.sup.1 is a trivalent aromatic group optionally having a
substituent. The trivalent aromatic group may be a trivalent
carbocyclic aromatic group or a trivalent heterocyclic aromatic
group. From the viewpoint of obtaining the desired effect of the
present invention in more favorable manner, it is preferable that
the trivalent aromatic group is the trivalent carbocyclic aromatic
group, more preferably a trivalent benzene ring group or a
trivalent naphthalene ring group, and further preferably a
trivalent benzene ring group or a trivalent naphthalene ring group
that is represented by the following formula.
[0227] In the following formulae, substituents Y.sup.1 and Y.sup.2
are described for the sake of convenience to clearly show a bonding
state (Y.sup.1 and Y.sup.2 have the same meanings as described
above, and the same applied to the following).
##STR00017##
[0228] Among these, it is preferable that A.sup.1 is a group
represented by each of the following formulae (A11) to (A25),
further preferably a group represented by the following formula
(A11), (A13), (A15), (A19), or (A23), and particularly preferably a
group represented by the following formula (A11) or (A23).
##STR00018## ##STR00019##
[0229] Examples of the substituent that may be included in the
trivalent aromatic group of A.sup.1 may include those exemplified
as the examples of the substituent in the aromatic group of A.sup.x
described above. It is preferable that A.sup.1 is a trivalent
aromatic group having no substituent.
[0230] A.sup.2 and A.sup.3 are each independently a divalent
alicyclic hydrocarbon group having 3 to 30 carbon atoms and
optionally having a substituent.
[0231] Examples of the divalent alicyclic hydrocarbon group having
3 to 30 carbon atoms may include a cycloalkanediyl group having 3
to 30 carbon atoms and a divalent alicyclic fused ring group having
10 to 30 carbon atoms.
[0232] Examples of the cycloalkanediyl group having 3 to 30 carbon
atoms may include a cyclopropanediyl group; a cyclobutanediyl group
such as a cyclobutane-1,2-diyl group and a cyclobutane-1,3-diyl
group; a cyclopentanediyl group such as a cyclopentane-1,2-diyl
group and a cyclopentane-1,3-diyl group; a cyclohexanediyl group
such as a cyclohexane-1,2-diyl group, a cyclohexane-1,3-diyl group,
and a cyclohexane-1,4-diyl group; a cycloheptanediyl group such as
a cycloheptane-1,2-diyl group, a cycloheptane-1,3-diyl group, and a
cycloheptane-1,4-diyl group; a cyclooctanediyl group such as a
cyclooctane-1,2-diyl group, a cyclooctane-1,3-diyl group, a
cyclooctane-1,4-diyl group, and a cyclooctane-1,5-diyl group; a
cyclodecanediyl group such as a cyclodecane-1,2-diyl group, a
cyclodecane-1,3-diyl group, a cyclodecane-1,4-diyl group, and a
cyclodecane-1,5-diyl group; a cyclododecanediyl group such as a
cyclododecane-1,2-diyl group, a cyclododecane-1,3-diyl group, a
cyclododecane-1,4-diyl group, and a cyclododecane-1,5-diyl group; a
cyclotetradecanediyl group such as a cyclotetradecane-1,2-diyl
group, a cyclotetradecane-1,3-diyl group, a
cyclotetradecane-1,4-diyl group, a cyclotetradecane-1,5-diyl group,
and a cyclotetradecane-1,7-diyl group; and a cycloeicosanediyl
group such as a cycloeicosane-1,2-diyl group and a
cycloeicosane-1,10-diyl group.
[0233] Examples of the divalent alicyclic fused ring group having
10 to 30 carbon atoms may include a decalindiyl group such as a
decalin-2,5-diyl group and a decalin-2,7-diyl group; an
adamantanediyl group such as an adamantane-1,2-diyl group and an
adamantane-1,3-diyl group; and a bicyclo[2.2.1]heptanediyl group
such as a bicyclo[2.2.1]heptane-2,3-diyl group, a
bicyclo[2.2.1]heptane-2,5-diyl group, and a
bicyclo[2.2.1]heptane-2,6-diyl group.
[0234] The divalent alicyclic hydrocarbon groups may further have a
substituent at any position. Examples of the substituent may
include those exemplified as the examples of the substituent in the
aromatic group of A.sup.x described above.
[0235] Among these, it is preferable that A.sup.2 and A.sup.3 are a
divalent alicyclic hydrocarbon group having 3 to 12 carbon atoms,
more preferably a cycloalkanediyl group having 3 to 12 carbon
atoms, further preferably a group represented by each of the
following formulae (A31) to (A34):
##STR00020##
[0236] and particularly preferably the group represented by the
aforementioned formula (A32).
[0237] The aforementioned divalent alicyclic hydrocarbon group
having 3 to 30 carbon atoms may exist in forms of cis- and
trans-stereoisomers that are based on difference of configuration
of carbon atoms bonded to Y.sup.1 and Y.sup.3 (or Y.sup.2 and
Y.sup.4). For example, when the group is a cyclohexane-1,4-diyl
group, a cis-isomer (A32a) and a trans-isomer (A32b) may exist, as
described below.
##STR00021##
[0238] In the present invention, the group may be a cis-isomer, a
trans-isomer, or an isomeric mixture of cis- and trans-isomers. It
is preferable that the group is the trans-isomer or the cis-isomer,
and more preferably the trans-isomer since orientation is
favorable.
[0239] A.sup.4 and A.sup.5 are each independently a divalent
aromatic group having 6 to 30 carbon atoms and optionally having a
substituent.
[0240] The aromatic groups of A.sup.4 and A.sup.5 may be monocyclic
or polycyclic.
[0241] Specific examples of preferable A.sup.4 and A.sup.5 are as
follows.
##STR00022##
[0242] The divalent aromatic groups of A.sup.4 and A.sup.5 may have
a substituent at any position. Examples of the substituent may
include a halogen atom, a cyano group, a hydroxyl group, an alkyl
group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6
carbon atoms, a nitro group, and a --C(.dbd.O)--OR.sup.8b group.
Herein, R.sup.8b is an alkyl group having 1 to 6 carbon atoms.
Among these, a halogen atom, an alkyl group having 1 to 6 carbon
atoms, and an alkoxy group are preferred. Of the halogen atom, a
fluorine atom is more preferred. Of the alkyl group having 1 to 6
carbon atoms, a methyl group, an ethyl group, and a propyl group
are more preferred. Of the alkoxy group, a methoxy group and an
ethoxy group are more preferred.
[0243] Among these, from the viewpoint of obtaining the desired
effect of the present invention in more favorable manner, it is
more preferable that A.sup.4 and A.sup.5 are each independently a
group represented by the following formulae (A41), (A42), or (A43)
that optionally have a substituent, and particularly preferable
that A.sup.4 and A.sup.5 are the group represented by the formula
(A41) that optionally has a substituent.
##STR00023##
[0244] Q.sup.1 is a hydrogen atom or an alkyl group having 1 to 6
carbon atoms and optionally having a substituent.
[0245] Examples of the alkyl group having 1 to 6 carbon atoms and
optionally having a substituent may include those exemplified as
the examples of A.sup.x described above.
[0246] Among these, it is preferable that Q.sup.1 is a hydrogen
atom or an alkyl group having 1 to 6 carbon atoms, and more
preferably a hydrogen atom or a methyl group.
[0247] The compound (I) may be produced by a reaction of a
hydrazine compound with a carbonyl compound, described in, e.g.,
International publication WO2012/147904.
[0248] [1.4.3. Polymerizable Monomer]
[0249] The composition (A) may contain a polymerizable monomer as
an optional component. Herein, the "polymerizable monomer"
represents, among compounds that have polymerization ability and
capability of acting as a monomer, the compound other than the
polymerizable liquid crystal compound having inverse wavelength
distribution. As the polymerizable monomer, for example, a monomer
having one or more polymerizable groups per molecule may be used.
When the polymerizable monomer has such a polymerizable group,
polymerization can be achieved in formation of the optically
anisotropic layer. When the polymerizable monomer is a
crosslinkable monomer having two or more polymerizable groups per
molecule, cross-linking polymerization can be achieved. Examples of
the polymerizable groups may include groups that are the same as
the groups of Z.sup.1--Y.sup.7-- and Z.sup.2--Y.sup.8-- in the
compound (I). More specific examples thereof may include an
acryloyl group, a methacryloyl group, and an epoxy group.
[0250] The polymerizable monomer itself may have liquid
crystallinity or non-liquid crystallinity. Herein, that the monomer
itself has "non-liquid crystallinity" means that even when the
polymerizable monomer itself is left at any temperature of room
temperature to 200.degree. C., the monomer does not exhibit
orientation on the first substrate that has been subjected to an
orientation treatment. The presence or absence of orientation is
determined by whether or not the presence or absence of light-dark
contrast appears during rotation of the rubbing direction in the
face in cross-Nicol transmission observation with a polarized light
microscope.
[0251] The content ratio of the polymerizable monomer in the
composition (A) is usually 1 to 100 parts by weight, and preferably
5 to 50 parts by weight, relative to 100 parts by weight of the
polymerizable liquid crystal compound having inverse wavelength
distribution. When the content ratio of the polymerizable monomer
is appropriately adjusted within such a range so as to exhibit
desired inverse wavelength distribution, the inverse wavelength
distribution is easily controlled with precision.
[0252] The polymerizable monomer may be produced by any known
production method. When the polymerizable monomer has a structure
similar to the compound (I), the polymerizable monomer may be
produced in a similar manner to the method for producing the
compound (I).
[0253] [1.4.4. Other Components in Composition (A)]
[0254] If necessary, the composition (A) may contain any optional
component such as those in the following examples, in addition to
the polymerizable liquid crystal compound and the polymerizable
monomer.
[0255] The composition (A) may contain a polymerization initiator.
The polymerization initiator may be appropriately selected
depending on the types of polymerizable groups of the polymerizable
liquid crystal compound, the polymerizable monomer, and another
polymerizable compound in the composition (A). For example, when
the polymerizable group is radical polymerizable, a radical
polymerization initiator may be used. When the polymerizable group
is anionic polymerizable, an anionic polymerization initiator may
be used. When the polymerizable group is cationic polymerizable, a
cationic polymerization initiator may be used.
[0256] As the radical polymerization initiator, any of a thermal
radical generator being a compound that generates active species
capable of initiating polymerization of the polymerizable compound
by heating; and a photo-radical generator being a compound that
generates active species capable of initiating polymerization of
the polymerizable compound by exposure of exposed light such as
visible light, ultraviolet light (i-line, etc.), far-ultraviolet
light, electron beam, and X-ray may be used. The photo-radical
generator is suitably used.
[0257] Examples of the photo-radical generator may include an
acetophenone-based compound, a biimidazole-based compound, a
triazine-based compound, an O-acyl oxime-based compound, an onium
salt-based compound, a benzoin-based compound, a benzophenone-based
compound, an .alpha.-diketone-based compound, a polynuclear
quinone-based compound, a xanthone-based compound, a diazo-based
compound, and an imide sulfonate-based compound, which are
described in International publication WO2012/147904.
[0258] Examples of the anionic polymerization initiator may include
an alkyl lithium compound; a monolithium salt or a monosodium salt
of biphenyl, naphthalene, and pyrene; and a polyfunctional
initiator such as a dilithium salt and a trilithium salt.
[0259] Examples of the cationic polymerization initiator may
include a protonic acid such as sulfuric acid, phosphoric acid,
perchloric acid, and trifluoromethanesulfonic acid; a Lewis acid
such as boron trifluoride, aluminum chloride, titanium
tetrachloride, and tin tetrachloride; and an aromatic onium salt,
and a combination of an aromatic onium salt with a reductant.
[0260] One type of the polymerization initiator may be used alone,
or two or more types thereof may be used in combination.
[0261] The content ratio of the polymerization initiator in the
composition (A) is usually 0.1 to 30 parts by weight, and
preferably 0.5 to 10 parts by weight, relative to 100 parts by
weight of the polymerizable compound.
[0262] The composition (A) may contain a surfactant for adjustment
of surface tension. The surfactant is not particularly limited. A
nonionic surfactant is usually preferable. As the nonionic
surfactant, a commercially available product may be used. Examples
thereof may include a nonionic surfactant that is an oligomer
having a molecular weight of several thousands, for example, KH-40
available from Seimi Chemical Co., Ltd. The content ratio of the
surfactant in the composition (A) is usually 0.01 to 10 parts by
weight, and preferably 0.1 to 2 parts by weight, relative to 100
parts by weight of the polymerizable compound.
[0263] The composition (A) may contain a solvent such as an organic
solvent. Examples of the organic solvent may include a ketone such
as cyclopentanone, cyclohexanone, methyl ethyl ketone, acetone, and
methyl isobutyl ketone; an acetate ester such as butyl acetate and
amyl acetate; a halogenated hydrocarbon such as chloroform,
dichloromethane, and dichloroethane; an ether such as 1,4-dioxane,
cyclopentyl methyl ether, tetrahydrofuran, tetrahydropyran,
1,3-dioxolane, and 1,2-dimethoxyethane; and an aromatic hydrocarbon
such as toluene, xylene, and mesitylene. The boiling point of the
solvent is preferably 60 to 250.degree. C., and more preferably 60
to 150.degree. C. from the viewpoint of excellent handleability.
The amount of the solvent to be used is usually 100 to 1,000 parts
by weight relative to 100 parts by weight of the polymerizable
compound.
[0264] The composition (A) may further contain an optional additive
such as a metal, a metal complex, a dye, a pigment, a fluorescent
material, a phosphorescent material, a leveling agent, a
thixotropic agent, a gelator, a polysaccharide, an ultraviolet
light absorber, an infrared light absorber, an antioxidant, an ion
exchange resin, and a metal oxide such as titanium oxide. The
content ratio of the optional additive in the polymerizable
composition of the present invention is usually 0.1 to 20 parts by
weight relative to 100 parts by weight of the polymerizable
compound.
[0265] The composition (A) may be usually prepared by mixing the
components described above.
[0266] [2. Optically Anisotropic Laminate]
[0267] The optically anisotropic laminate of the present invention
is obtained by separating the optically anisotropic layer from the
multilayer film of the present invention and attaching the
optically anisotropic layer to a second long-length substrate.
[0268] One example of the second substrate is a film capable of
protecting the optically anisotropic layer, such as a masking film.
As the masking film, any known films (for example, FF1025 and
"FF1035" available from Tredegar Corporation; "SAT116T",
"SAT2038T-JSL", and "SAT4538T-JSL" available from Sun A. Kaken Co.,
Ltd.; "NBO-0424", "TFB-K001", "TFB-K0421", and "TFB-K202" available
from Fujimori Kogyo Co., Ltd.; "DT-2200-25" and "K-6040" available
from Hitachi Chemical Co., Ltd.; and "6010#75", "6010#100",
"6011#75", and "6093#75" available from Teraoka Seisakusho Co.,
Ltd.) may be used. From the optically anisotropic laminate having
such a second substrate, the optically anisotropic layer can be
easily transferred to another member. Therefore, an optical element
having the optically anisotropic layer can be easily
manufactured.
[0269] Another example of the second substrate is a substrate film
having optical isotropy. Optical isotropy specifically represents
that the in-plane retardation Re is preferably less than 10 nm, and
more preferably less than 5 nm. In an optically isotropic
substrate, it is preferable that the retardation Rth in a thickness
direction is also less than 10 nm, and more preferably less than 5
nm. The retardation Rth in the thickness direction is calculated by
the following equation.
Rth=[{(nx+ny)/2}-nz].times.d
(In the equation, nx is a refractive index of the substrate film in
an in-plane slow axis direction (maximum in-plane refractive
index), ny is a refractive index of the substrate film in a
direction orthogonal to the in-plane slow axis direction, nz is a
refractive index of the substrate film in the thickness direction,
and d is the thickness (nm) of the substrate film.)
[0270] Examples of the material for the optical isotropic substrate
film may include a cellulose ester in addition to those exemplified
as the examples of the first substrate film described above. A
long-length film of such a material is formed, and the long-length
film as it is may be used without stretching as the second
substrate. The optically anisotropic laminate having the optically
isotropic substrate film as the second substrate as it is may be
incorporated into an optical device such as a display device, and
may be used as an optical member.
[0271] In manufacturing of the optically anisotropic laminate of
the present invention, a step of separating the optically
anisotropic layer from the multilayer film and attaching the
optically anisotropic layer to the second long-length substrate may
be performed by a roll-to-roll operation.
[0272] [3. Circular Polarizing Plate]
[0273] The circular polarizing plate of the present invention is
obtained by attaching one or more layers of the optically
anisotropic layer to a long-length linear polarizer by a
roll-to-roll process.
[0274] Specific aspects of the circular polarizing plate of the
present invention may include two aspects described below.
[0275] Circular polarizing plate (i): a circular polarizing plate
obtained by attaching the optically anisotropic layer to a
long-length linear polarizer by a roll to roll process, wherein the
optically anisotropic layer is a layer separated from the
multilayer film of the present invention. Circular polarizing plate
(ii): a circular polarizing plate obtained by attaching a
long-length .lamda./4 wave plate, a long-length .lamda./2 wave
plate, and a long-length linear polarizer by a roll to roll
process, wherein the long-length .lamda./4 wave plate, the
long-length .lamda./2 wave plate, or both the wave plates are the
optically anisotropic layer separated from the multilayer film of
the present invention.
[0276] As the optically anisotropic layer contained in the circular
polarizing plate of the present invention, the optically
anisotropic layer separated from the multilayer film of the present
invention may be used as it is. Alternatively, as the optically
anisotropic layer contained in the circular polarizing plate of the
present invention, the optically anisotropic layer that is
separated from the multilayer film of the present invention and
attached to the second substrate to form the optically anisotropic
laminate of the present invention may be used as it is, and the
optically anisotropic layer that is further separated from the
optically anisotropic laminate may also be used.
[0277] Any of a step of separating the optically anisotropic layer
from the multilayer film and a step of attaching the optically
anisotropic layer to another layer (another optically anisotropic
layer, linear polarizer, etc.) may be first performed. For example,
the separating step and the attaching step may be performed by
attaching a face of the multilayer film on an optically anisotropic
layer side to a face of the linear polarizer and then separating
the first substrate.
[0278] In the circular polarizing plate (ii), relationship of the
slow axis of the .lamda./4 wave plate, the slow axis of the
.lamda./2 wave plate, and the transmission axis of the linear
polarizer may be various known relationship. For example, when the
optically anisotropic layer of the multilayer film of the present
invention is used for both the .lamda./4 wave plate and the
.lamda./2 wave plate, a relationship in which the angle of the
direction of slow axis of the .lamda./2 wave plate relative to the
direction of transmission axis of the polarizer is 15.degree. or an
angle close to 15.degree. (for example, 15.degree..+-.5.degree.,
preferably 15.degree..+-.4.degree., and more preferably)
15.degree..+-.3.degree. and the angle of the direction of slow axis
of the 1/4.lamda. wave plate relative to the direction of
transmission axis of the polarizer is 75.degree. or an angle close
to 75.degree. (for example, 75.degree..+-.5.degree., preferably
75.degree..+-.4.degree., and more preferably)
75.degree..+-.3.degree. may be established. With such an aspect,
the circular polarizing plate may be used as a broad wavelength
range anti-reflective film for an organic EL display device.
[0279] In a product according to the present invention (multilayer
film, circular polarizing plate, display device, etc.), a
relationship of angle formed between a direction of an in-plane
optical axis (slow axis, transmission axis, transmission axis,
etc.) and a geometric direction (the lengthwise direction and
widthwise direction of the film, etc.) are defined as follows. A
shift in a certain direction is positive, and a shift in the other
direction is negative. The positive and negative directions are
commonly defined in components of the product. For example, in a
circular polarizing plate, the direction of slow axis of the
.lamda./2 wave plate relative to the direction of transmission axis
of the linear polarizer is 15.degree. and the direction of slow
axis of the 1/4.lamda. wave plate relative to the direction of
transmission axis of the linear polarizer is 75.degree. ''
represents two cases described below:
[0280] When the circular polarizing plate is observed from one face
thereof, the direction of slow axis of the .lamda./2 wave plate
shifts clockwise by 15.degree. from the direction of transmission
axis of the linear polarizer and the direction of slow axis of the
1/4.lamda. wave plate shifts clockwise by 75.degree. from the
direction of transmission axis of the linear polarizer.
[0281] When the circular polarizing plate is observed from one face
thereof, the direction of slow axis of the .lamda./2 wave plate
shifts counterclockwise by 15.degree. from the direction of
transmission axis of the linear polarizer and the direction of slow
axis of the 1/4.lamda. wave plate shifts counterclockwise by
75.degree. from the direction of transmission axis of the linear
polarizer.
[0282] A specific aspect of the circular polarizing plate (i) may
be an aspect in which the circular polarizing plate has one layer
of .lamda./4 wave plate as an optically anisotropic layer and the
angle of the direction of slow axis of the .lamda./4 wave plate
relative to the transmission axis of the linear polarizer is
45.degree. or an angle close to 45.degree. (for example,
45.degree..+-.5.degree., preferably 45.degree..+-.4.degree., and
more preferably 45.degree..+-.3.degree.). With such an aspect, the
circular polarizing plate may be used as an anti-reflective film
for an organic EL display device.
[0283] Attaching by a roll-to-roll process represents an aspect in
which a step of feeding out a film from a roll of long-length film,
conveying the film, and attaching the film to another film on a
conveyance line is performed, and the attached product is wound
into a take-up roll. For example, when the linear polarizer and the
multilayer film are attached, a step of feeding out the multilayer
film from a roll of long-length multilayer film, conveying the
film, and attaching the film to the linear polarizer on a
conveyance line is performed, and the attached product is wound
into a take-up roll. Thus, attaching by a roll-to-roll process may
be performed. In this case, the linear polarizer may also be
supplied to the attaching step by feeding out from a roll.
[0284] As the linear polarizer, any known polarizers used for a
device such as a liquid crystal display device and other optical
devices may be used. Examples of the linear polarizer may include a
linear polarizer obtained by effecting adsorption of iodine or
dichroic dye to a polyvinyl alcohol film, and uniaxially stretching
the film in a boric acid bath, and a linear polarizer obtained by
effecting absorption of iodine or dichroic dye to a polyvinyl
alcohol film, stretching the film, and modifying one moiety of
polyvinyl alcohol unit in the molecular chain into a polyvinylene
unit. Other examples of the linear polarizer may include a
polarizer having a function of separating light into polarized
reflected light and transmitted light, such as a grid polarizer, a
multi-layer polarizer, and a cholesteric liquid crystal polarizer.
Among these, a polarizer containing polyvinyl alcohol is
preferred.
[0285] When natural light reaches the polarizer used in the present
invention, only one polarized light passes therethrough. The
polarization degree of the polarizer used in the present invention
is not particularly limited, and is preferably 98% or more, and
more preferably 99% or more. The average thickness of the polarizer
is preferably 5 to 80 .mu.m.
[0286] One of applications of the circular polarizing plate of the
present invention may be an application as an anti-reflective film
for a display device having an organic EL element. Specifically,
the circular polarizing plate having the aforementioned
configuration is provided on a surface of the display device so
that a face on a linear polarizer side is disposed toward a visual
observation side. This can suppress radiation of light that has
entered from the outside of the display device and then been
reflected within the display device to the outside of the display
device. As a result, undesired phenomena in light such as glare on
a display face of the display device can be suppressed.
Specifically, among the light that has entered from the outside of
the device, only a part of linearly polarized light passes through
the linear polarizer, and then passes through the optically
anisotropic layer, resulting in circularly polarized light. The
circularly polarized light herein includes elliptically polarized
light as long as an anti-reflection function is substantially
expressed. The circularly polarized light is reflected on a
component that reflects light in the display device (reflection
electrode in the organic EL element, etc.), and then passes through
the optically anisotropic layer again, resulting in linearly
polarized light having a polarization axis in a direction
orthogonal to the polarization axis of the linear polarizer having
entered. Thus, the light does not pass through the liner polarizer.
The anti-reflection function can thereby be achieved. In
particular, the circular polarizing plate (ii) described above can
achieve the anti-reflection function at a broad wavelength range.
Since the circular polarizing plate of the present invention has a
reduced number of defects due to a heterogeneous matter in the
optically anisotropic layer, the effect of anti-reflection can be
obtained in particularly favorable manner. For example, an
optically anisotropic layer having a relationship of
three-dimensional refractive indices (nx, ny, and nz) that
satisfies "nx>ny=nz", "nx>ny>nz", or "nx>nz>ny" can
be used. When an optically anisotropic layer having a relationship
of three-dimensional refractive indices of "nx>nz>ny" is
used, the circular polarizing plate has not only an anti-reflection
function in a frontal direction but also an anti-reflection
function in a diagonal direction.
[0287] The circular polarizing plate of the present invention may
have another optional layer, if necessary. Examples of the optional
layer may include an adhesion layer for adhesion to another member,
a mat layer for improving the sliding property of the film, a
hard-coat layer such as an impact-resistant polymethacrylate resin
layer, an anti-reflection layer, and an anti-fouling layer.
[0288] [4. Display Device]
[0289] The circular polarizing plate of the present invention may
be used as a component of a display device such as a liquid crystal
display device and an organic EL display device. As a particularly
preferable aspect, the organic EL display device of the present
invention comprises the circular polarizing plate of the present
invention. Specifically, the organic EL display device of the
present invention is a display device having an organic EL element
as a display element in which the circular polarizing plate of the
present invention may be provided as the anti-reflective film, as
described above.
[0290] [5. Resin Film (X)]
[0291] The resin film disclosed in this application (hereinafter
referred to as "resin film (X)") is a resin film that is formed on
a long-length substrate and contains a cured liquid-crystal
molecules. The "cured liquid-crystal molecules" means as described
in the section of [1. Multilayer Film]. Examples of the cured
liquid-crystal molecules may include a polymer obtained by
polymerizing the polymerizable liquid crystal compound. In the
following description, the "resin film (X) containing the cured
liquid-crystal molecules" is sometimes abbreviated as "liquid
crystal resin film". The resin film (X) may be used as the
optically anisotropic layer in the multilayer film of the present
invention.
[0292] [5.1. Substrate]
[0293] The substrate has a slow axis in a direction different from
the widthwise direction thereof. Unless otherwise specified, the
directions of slow axes of the substrate and the resin film (X)
used herein represent a direction of slow axis in an in-plane
direction. "Difference" between the slow axis direction and the
widthwise direction means that the angle formed between the slow
axis direction and the widthwise direction is 5.degree. or more.
The upper limit of the angle formed between the slow axis direction
and the widthwise direction is not particularly limited, and may
be, for example, 90.degree. or less. The angle formed between the
slow axis direction and the widthwise direction may be
appropriately adjusted depending on a desired performance required
for the liquid crystal resin film, and for example, may be
45.degree..+-.3.degree. or 22.5.degree..+-.3.degree.. When the
substrate has such a slow axis, homogeneous orientation regularity
in substantially the same direction as the slow axis direction can
be imparted to the resin film (X) formed on the substrate.
[0294] The material for the substrate is not particularly limited.
Various resins capable of imparting an orientation-controlling
force to the surface of the substrate by imparting birefringence
can be used.
[0295] Specifically, the same material as the material for the
first substrate described in the section of [1.1. First Substrate]
may be used.
[0296] As the method for providing the substrate with a slow axis,
a stretching method may be typically adapted. Specifically, a film
formed from the aforementioned material is stretched to impart
anisotropy, to thereby prepare a substrate having a slow axis. The
stretching direction may be appropriately set depending on the
desired orientation direction required for the liquid crystal resin
film. The stretching may be performed by only diagonal stretching
or a combination of diagonal stretching, lengthwise stretching
(stretching in the lengthwise direction of the substrate), and/or
widthwise stretching (stretching in the widthwise direction of the
substrate). The stretching ratio may be appropriately set so that
the birefringence .DELTA.n of the substrate falls within a desired
range. The lower limit of birefringence .DELTA.n of the substrate
is preferably 0.000050 or more, and more preferably 0.000070 or
more. On the other hand, the upper limit of birefringence .DELTA.n
of the substrate is preferably 0.007500 or less, and more
preferably 0.007000 or less. In particular, when the aforementioned
resin containing the alicyclic structure-containing polymer or the
resin containing triacetylcellulose is used as the material for the
substrate, and a birefringence equal to or more than the lower
limit is imparted, a favorable orientation-controlling force can be
imparted to the surface of the substrate. When the birefringence is
equal to or less than the aforementioned upper limit, the liquid
crystal resin film can be used for various applications such as a
.lamda./4 wave plate without separation from the substrate. The
stretching may be performed by any known stretching machines such
as a tenter stretching machine.
[0297] [5.2. Formation of Liquid Crystal Resin Film on
Substrate]
[0298] The formation of the liquid crystal resin film on the
substrate may be typically performed by a method including:
[0299] Step (i): a step of applying onto the substrate the liquid
crystal composition containing the polymerizable liquid crystal
compound to form a layer of the liquid crystal composition;
[0300] Step (ii): a step of giving homogeneous orientation to the
polymerizable liquid crystal compound in the layer of the liquid
crystal composition, the orientation being in substantially the
same direction as the direction of slow axis of the substrate;
and
[0301] Step (iii): a step of polymerizing the polymerizable liquid
crystal compound to form the cured liquid-crystal molecules
(hereinafter referred to as "method (X)).
[0302] Step (i) may be performed by applying the liquid crystal
composition onto one surface of the continuously conveyed
substrate. Examples of the applying method may include a curtain
coating method, an extrusion coating method, a roll coating method,
a spin coating method, a dip coating method, a bar coating method,
a spray coating method, a slide coating method, a printing coating
method, a gravure coating method, a die coating method, a cap
coating method, and a dipping method. The thickness of layer of the
liquid crystal composition to be applied may be appropriately set
depending on a desired thickness required for the liquid crystal
resin film.
[0303] Step (ii) may be achieved immediately by coating, but if
necessary, be achieved by an orientation treatment such as heating
after coating. Conditions of the orientation treatment may be
appropriately set depending on the properties of the liquid crystal
composition to be used. For example, the conditions may be
treatment conditions at a temperature of 50 to 160.degree. C. for
30 seconds to 5 minutes. When the composition and treatment
conditions of the liquid crystal composition to be used are
appropriately set, homogeneous orientation in substantially the
same direction as the direction of slow axis of the substrate can
be achieved.
[0304] Step (iii) may be performed immediately after Step (ii).
Alternatively, a step of drying the layer of the liquid crystal
composition may be performed, if necessary, before Step (iii) and
after Step (ii). The drying may be achieved by a drying method such
as air drying, heated-air drying, drying under reduced pressure,
and heated-air drying under reduced pressure. By the drying, a
solvent can be removed from the layer of the liquid crystal
composition.
[0305] At Step (iii), a method that is suitable for the properties
of components of the liquid crystal composition such as the
polymerizable compound and the polymerization initiator may be
appropriately selected. Examples of the method may include a method
of irradiation with an active energy beam and a thermal
polymerization method. The method of irradiation with an active
energy beam is preferred since a reaction can proceed at room
temperature without heating. Examples of the active energy beam for
irradiation in this method may include light such as visible light,
ultraviolet light, and infrared light, and any energy beam such as
an electron beam. A method of irradiation with light such as
ultraviolet light is preferred because of simple operation. The
upper limit of temperature during irradiation with ultraviolet
light is preferably equal to or lower than the glass transition
temperature (Tg) of the substrate. The upper limit of temperature
usually falls within a range of 150.degree. C. or lower, preferably
100.degree. C. or lower, and particularly preferably 80.degree. C.
or lower. The lower limit of temperature during irradiation with
ultraviolet light may be 15.degree. C. or higher. The irradiation
intensity of ultraviolet light usually falls within a range of 0.1
mW/cm.sup.2 to 1,000 mW/cm.sup.2, and preferably 0.5 mW/cm.sup.2 to
600 mW/cm.sup.2.
[0306] [5.3. Liquid Crystal Resin Film]
[0307] In the resin film (X), the cured liquid-crystal molecules
may have homogeneous orientation regularity in substantially the
same direction as the direction of slow axis of the substrate.
[0308] When the cured liquid-crystal molecules are obtained by
polymerizing the polymerizable liquid crystal compound, the
long-axis direction of mesogen of the polymerizable liquid crystal
compound is the long-axis direction of mesogen of the cured
liquid-crystal molecules. When a plurality of types of mesogens
having different orientation directions exist in the liquid crystal
resin film in, e.g., the instance of using the polymerizable liquid
crystal compound having inverse wavelength distribution as the
polymerizable liquid crystal compound, a direction in which the
long-axis direction of mesogen of the longest type among them is
aligned is referred to as the alignment direction.
[0309] Further, the orientation in "substantially" the same
direction as the direction of slow axis of the substrate means that
the angle formed between the direction of slow axis of the
substrate and the alignment direction of mesogen is 5.degree. or
less. The angle is preferably 3.degree. or less, and more
preferably 1.degree. or less.
[0310] When the substrate has a specific slow axis described above
and the material for the liquid crystal resin film is appropriately
selected, homogeneous orientation regularity in substantially the
same direction as the slow axis direction can be imparted to the
resin film (X) formed on the substrate. As a result, the liquid
crystal resin film having such specific orientation regularity can
be obtained.
[0311] The thickness of the liquid crystal resin film is not
particularly limited, and may be appropriately adjusted so that
properties such as retardation fall within a desired range.
Specifically, the lower limit of the thickness is preferably 0.5
.mu.m or more, and more preferably 1.0 .mu.m or more, whereas the
upper limit of the thickness is preferably 10 .mu.m or less, and
more preferably 7 .mu.m or less.
[0312] The shape, length, and width of the liquid crystal resin
film are not particularly limited, and may be those of long-length
film having the same shape as that of the substrate. This liquid
crystal resin film may be cut into a shape such as a rectangle
suitable for desired application, if necessary.
[0313] It is preferable that the resin film (X) has inverse
wavelength distribution. That is, it is preferable that the resin
film (X) has wavelength distribution that exhibits higher in-plane
phase difference for transmitted light having longer wavelength as
compared with transmitted light having shorter wavelength. It is
preferable that the resin film (X) has inverse wavelength
distribution at at least a part or preferably all of visible light
region. When the liquid crystal resin film has inverse wavelength
distribution, the function can be uniformly expressed over a wide
region for optical applications such as a .lamda./4 wave plate and
a .lamda./2 wave plate.
[0314] As the polymerizable liquid crystal compound such as the
polymerizable liquid crystal compound having inverse wavelength
distribution and the liquid crystal composition containing the
polymerizable liquid crystal compound, the same compound and
composition as described above as the materials for the optically
anisotropic layer may be used.
[0315] [6. .lamda./4 Wave Plate (X)]
[0316] The resin film (X) may be used for optical applications such
as a phase difference plate, and in particular, as a wave plate
such as a .lamda./4 wave plate and a .lamda./2 wave plate. In
particular, the resin film (X) is preferably used as a component of
a .lamda./4 wave plate (X) described below.
[0317] The .lamda./4 wave plate (X) comprises the resin film (X).
The .lamda./4 wave plate (X) may be composed only of the resin film
(X). Specifically, the liquid crystal resin film formed on the
substrate film is separated from the substrate, and cut into a
desired shape suitable for the application such as a rectangle, and
the cut liquid crystal resin film may be used as the .lamda./4 wave
plate (X).
[0318] The .lamda./4 wave plate (X) may include a substrate in
addition to the resin film (X). Specifically, a laminate of the
substrate and the liquid crystal resin film may be used as the
.lamda./4 wave plate (X) without separation of the liquid crystal
resin film formed on the substrate film from the substrate. When as
the substrate, a preferable material such as the alicyclic
structure-containing polymer or the cellulose ester is selected,
the optical anisotropy may be decreased while high
orientation-controlling force imparted by stretching is held.
Therefore, a laminate having such a substrate as it is may be used
as the .lamda./4 wave plate (X).
[0319] The .lamda./4 wave plate (X) may have another optional
layer, if necessary. Examples of the optional layer may include an
adhesion layer for adhesion to another member, a mat layer for
improving the sliding property of the film, a hard-coat layer such
as an impact-resistant polymethacrylate resin layer, an
anti-reflection layer, and an anti-fouling layer.
[0320] [7. Circular Polarizing Plate (X)]
[0321] The .lamda./4 wave plate (X) is preferably used as a
component of a circular polarizing plate (X) described below.
[0322] The circular polarizing plate (X) is provided with the
.lamda./4 wave plate (X). The circular polarizing plate (X) may
have a linear polarizer in addition to the .lamda./4 wave plate
(X).
[0323] As the linear polarizer, any known polarizers used in a
device such as a liquid crystal display device may be used.
Examples of the linear polarizer may include a linear polarizer
obtained by effecting adsorption of iodine or dichroic dye to a
polyvinyl alcohol film, and uniaxially stretching the film in a
boric acid bath, and a linear polarizer obtained by effecting
adsorption of iodine or dichroic dye to a polyvinyl alcohol film,
stretching the film, and modifying one moiety of polyvinyl alcohol
unit in the molecular chain into a polyvinylene unit. Other
examples of the linear polarizer may include a polarizer having a
function of separating light into polarized reflected light and
transmitted light, such as a grid polarizer, a multi-layer
polarizer, and a cholesteric liquid crystal polarizer. Among these,
a polarizer containing polyvinyl alcohol is preferred.
[0324] When natural light reaches the circular polarizing plate,
only one polarized light passes therethrough. The polarization
degree of the polarizer used for the circular polarizing plate (X)
is not particularly limited, and is preferably 98% or more, and
more preferably 99% or more. The average thickness of the polarizer
is preferably 5 to 80 .mu.m.
[0325] When the .lamda./4 wave plate (X) is used for the circular
polarizing plate (X), it is preferable that the phase difference at
a wavelength of 550 nm is 137.5 nm or a value close to 137.5 nm,
specifically 100 to 150 nm. In the circular polarizing plate (X),
it is preferable that the angle formed between a slow axis of the
.lamda./4 wave plate (X) and a transmission axis of the linear
polarizer is 45.degree. or an angle close to 45.degree.,
specifically 40 to 50.degree.. When the circular polarizing plate
has such a phase difference and such an angle, the circular
polarizing plate may be usefully used for an application such as a
component of the liquid crystal display device.
[0326] One of applications of the circular polarizing plate having
such a configuration may be an application as an anti-reflective
film for a display device having an organic EL element.
Specifically, the circular polarizing plate (X) having the
aforementioned configuration is provided on a surface of the
display device so that a face on a linear polarizer side is
disposed toward a visual observation side. This can suppress
radiation of light that has entered from the outside of the display
device and then been reflected within the display device to the
outside of the display device. As a result, undesired phenomena in
light such as glare on a display face of the display device can be
suppressed. Specifically, among the light that has entered from the
outside of the device, only a part of linearly polarized light
passes through the linear polarizer, and then passes through the
.lamda./4 wave plate, resulting in circularly polarized light. The
circularly polarized light herein includes elliptically polarized
light as long as an anti-reflection function is substantially
expressed. The circularly polarized light is reflected on a
component that reflects light in the display device (reflection
electrode in the organic EL element, etc.), and then passes through
the .lamda./4 wave plate again, resulting in linearly polarized
light having a polarization axis in a direction orthogonal to the
polarization axis of the linear polarizer having entered. Thus, the
light does not pass through the liner polarizer. The
anti-reflection function can thereby be achieved.
[0327] The circular polarizing plate (X) may have an optional
component such as those which the component of the .lamda./4 wave
plate (X) may have.
[0328] [8. Display Device (X)]
[0329] The .lamda./4 wave plate (X) and the circular polarizing
plate (X) may be used as a component of a display device such as a
liquid crystal display and an organic EL display device. Examples
of particularly preferable aspect may include an organic EL display
device having the circular polarizing plate (X). Specifically, the
organic EL display device (X) is a display device having an organic
EL element as a display element in which the circular polarizing
plate (X) may be provided as the anti-reflective film, as described
above.
[0330] The resin film (X) may be used for a material for a phase
difference plate such as the .lamda./4 wave plate (X). The resin
film (X) is capable of uniformly expressing phase difference in the
plane, can be efficiently manufactured, and has a reduced number of
defects due to generation of a heterogeneous matter. According to
the method (X), the resin film (X) may be efficiently
manufactured.
[0331] In particular, when a substrate having a birefringence
.DELTA.n of 0.000050 or more is used, particularly favorable
orientation-controlling force can be expressed. Further, when the
resin film (X) having inverse wavelength distribution is formed
using the polymerizable liquid crystal compound having inverse
wavelength distribution as a material for the cured liquid-crystal
molecules, the resin film (X) that has high manufacturing
efficiency by diagonal stretching, high degree of design freedom of
slow axis direction, uniform properties in the plane, a reduced
number of defects due to a heterogeneous matter, and high-level of
usefulness due to inverse wavelength distribution, all of which are
at high levels, can be provided.
[0332] The .lamda./4 wave plate (X), the circular polarizing plate
(X), and the organic EL display device (X) are a .lamda./4 wave
plate, a circular polarizing plate, and an organic
electroluminescent display device, respectively, that have uniform
properties, can be efficiently manufactured, and have a reduced
number of defects due to generation of a heterogeneous matter.
EXAMPLES
[0333] Hereinafter, the present invention will be specifically
described with reference to Examples. However, the present
invention is not limited to Examples described below. The present
invention may be implemented with any modifications without
departing from the scope of claims of the present invention and
equivalents thereof.
[0334] Unless otherwise specified, "%" and "part(s)" that represent
an amount in the following description are based on weight. Unless
otherwise specified, operations described below were performed
under conditions of normal temperature and normal pressure.
[0335] Hereinafter, Examples 1 to 12 and Comparative Example 1 will
first be described, and Reference Examples 1 to 6 and Reference
Comparative Example 1 will then be described.
Measurement Methods in Examples 1 to 12 and Comparative Example
1
[0336] [1. Method for Measuring In-Plane Retardation and Slow Axis
Direction]
[0337] The in-plane retardation and the slow axis direction of the
first substrate and the optically anisotropic layer were measured
at a measurement wavelength of 550 nm by AxoScan (manufactured by
Axometrics, Inc.). The in-plane retardation and the slow axis
direction of the optically anisotropic layer were measured in a
sample obtained by transferring the optically anisotropic layer to
a glass plate.
[0338] [2. Method for Evaluating Orientation State]
[0339] A sample was prepared by transferring the optically
anisotropic layer to a glass plate. The sample was disposed between
two linear polarizers (polarizer and analyzer). At that time, the
polarizers were disposed so that polarized light transmission axes
of the polarizers were orthogonal to each other as viewed in a
thickness direction. The slow axis direction of the optically
anisotropic layer was set so as to be parallel or orthogonal to the
polarized light transmission axes of the linear polarizers as
viewed in the thickness direction. A transmittance of light through
this sample (transmittance under crossed Nicols) was measured by a
spectrophotometer "V7200" and an automated polarizing film
measurement device "VAP-7070S" manufactured by JASCO Corporation,
and evaluated in accordance with the following criteria.
[0340] Excellent: the transmittance under crossed Nicols at the
bottom wavelength was 0.010% or less.
[0341] Good: the transmittance under crossed Nicols at the bottom
wavelength was more than 0.010% and 0.020% or less.
[0342] Passable: the transmittance under crossed Nicols at the
bottom wavelength was more than 0.020% and 0.030% or less.
[0343] Bad: the transmittance under crossed Nicols at the bottom
wavelength was more than 0.030%.
[0344] [3. Method for Evaluating Orientation Defects]
[0345] The liquid crystal resin layer was observed by a polarized
light microscope, and evaluated by the presence or absence of line
defects in the liquid crystal resin layer in accordance with the
following criteria. Herein, the line defects represent linearly
extending defects of orientation as shown in FIG. 1.
[0346] Good: line defects did not exist.
[0347] Bad: line defects existed.
[0348] [4. Method for Evaluating Bright Spot and Heterogeneous
Matter]
[0349] The optically anisotropic layer was observed by a polarized
light microscope, and visually evaluated by the presence or absence
of a bright spot and a heterogeneous matter in the optically
anisotropic layer.
[0350] Good: the number of bright spots and heterogeneous matters
per square meter is 5 or less.
[0351] Bad: the number of bright spots and heterogeneous matters
per square meter is 6 or more.
[0352] [5. Visual Observation of Circular Polarizing Plate]
[0353] The circular polarizing plate was disposed on a diffuse
reflection plate (product name: "Metalumy TS50" available from
Toray Industries, Inc., aluminum-deposited polyethylene
terephthalate (PET) film), and the front contrast and viewing angle
characteristics were evaluated in accordance with the following
criteria.
[0354] The front contrast was visually observed from the front
(that is, in a direction perpendicular to a face of the circular
polarizing plate) and evaluated on the basis of observed reflection
color. A case where the reflection color was particularly black was
evaluated "A" (excellent). A case where the reflection color was
black was evaluated "B" (good). A case where the reflection color
was bright and blue was evaluated "C" (bad).
[0355] The viewing angle characteristics were visually observed
from the front and at an angle of 45.degree. and evaluated on the
basis of reflection color, brightness, and color unevenness.
[0356] A case where the reflection color and the brightness
observed from the front were not different from those observed at
an angle of 45.degree. and the color unevenness was not recognized
in the observation at an angle of 45.degree. was evaluated as "A"
(excellent).
[0357] A case where the reflection color and the brightness
observed from the front were not different from those observed at
an angle of 45.degree. and the color unevenness was not almost
recognized in the observation at an angle of 45.degree. was
evaluated as "B" (good).
[0358] A case where the reflection color and the brightness
observed from the front were different from those observed at an
angle of 45.degree. and the color unevenness was slightly
recognized in the observation at an angle of 45.degree. was
evaluated as "C" (usable but not good).
[0359] A case where the reflection color and the brightness
observed from the front were different from those observed at an
angle of 45.degree. and the color unevenness was clearly recognized
in the observation at an angle of 45.degree. was evaluated as "D"
(bad).
Production Example 1
Preparation of Pre-Stretch Substrate (A)
[0360] Pellets of thermoplastic norbornene resin (product name
"ZEONOR1420R" available from ZEON CORPORATION, Tg: 137.degree. C.)
were dried at 90.degree. C. for 5 hours. The dried pellets were
supplied to an extruder, melted in the extruder, passed through a
polymer pipe and a polymer filter, and extruded from a T-die on a
casting drum to be in a sheet shape. The sheet was cooled, and
wound while the sheet was protected with a masking film (FF1025
available from Tredegar Corporation). As a result, a roll of
pre-stretch substrate (A) having a thickness of 80 .mu.m and a
width of 1,490 mm was obtained.
Production Example 2
Preparation of Pre-Stretch Substrate (B)
[0361] A roll of pre-stretch substrate (B) having a thickness of 50
.mu.m and a width of 675 mm was obtained in the same manner as in
Production Example 1 except that a T-die was changed.
Production Example 3
Preparation of Pre-Stretch Substrate (C)
[0362] A roll of pre-stretch substrate (C) having a thickness of 80
.mu.m and a width of 1,490 mm was obtained in the same manner as in
Production Example 1 except that the pellet of thermoplastic
norbornene resin were changed to pellets of another norbornene
resin (available from ZEON CORPORATION, Tg: 126.degree. C.)
Production Example 4
Preparation of Liquid Crystal Composition (A)
[0363] 24.15 parts of a polymerizable liquid crystal compound
(product name "LC242" available from BASF, a compound represented
by a formula (A1)), 0.12 parts of a surfactant (product name
"FTERGENT FTX-209F" available from Neos Company Limited), 0.73
parts by weight of a polymerization initiator (product name
"IRGACURE379" available from BASF), and 75.00 parts of a solvent
(methyl ethyl ketone) were mixed to prepare a liquid crystal
composition.
##STR00024##
Production Example 5
Preparation of Liquid Crystal Composition (B)
[0364] 21.25 parts of a polymerizable liquid crystal compound
having inverse wavelength distribution represented by a formula
(B1), 0.11 parts of a surfactant (product name "Surflon 5420"
available from AGC Seimi Chemical Co., Ltd.), 0.64 parts of a
polymerization initiator (product name "IRGACURE379" available from
BASF), and 78.00 parts of a solvent (cyclopentanone available from
ZEON CORPORATION) were mixed to prepare a liquid crystal
composition.
##STR00025##
Example 1
(1-1. Preparation of First Substrate)
[0365] The pre-stretch substrate (A) was drawn from the roll of
pre-stretch substrate (A) obtained in Production Example 1, the
masking film was continuously separated, and the pre-stretch
substrate was supplied to a tenter stretching machine. The
pre-stretch substrate was diagonally stretched such that slow axis
of the substrate film is formed at an angle of 15.degree. relative
to the widthwise direction (75.degree. relative to the lengthwise
direction), and both ends of the substrate in the widthwise
direction of the substrate film were trimmed. Thus, a long-length
first substrate (A-1) having a width of 1,350 mm was obtained. The
Re of the obtained first substrate (A-1) was 265 nm and the film
thickness thereof was 40 The obtained first substrate (A-1) was
wound while the first substrate was protected with a new masking
film (FF1025 available from Tredegar Corporation). Thus, a roll of
the first substrate (A-1) was obtained. The value of .DELTA.n
calculated by (Re(nm))/(film thickness (.mu.m).times.1,000) was
0.006625.
[0366] (1-2. Formation of Layer of Liquid Crystal Composition)
[0367] The first substrate (A-1) was fed out from the roll of the
first substrate (A-1) obtained in (1-1), the masking film was
separated, and the first substrate was conveyed. The liquid crystal
composition (A) obtained in Production Example 4 was directly
applied onto one face of the conveyed first substrate (A-1) (face
on a side that had been attached to the masking film) by a die
coater at a room temperature of 25.degree. C. to form a layer of
the liquid crystal composition.
[0368] (1-3. Orientation Treatment and Polymerization)
[0369] The layer of the liquid crystal composition on the first
substrate (A-1), obtained in (1-2), was subjected to an orientation
treatment at 110.degree. C. for 2.5 minutes. The layer of the
liquid crystal composition was then irradiated with ultraviolet
light having an integrated illuminance of 100 mJ/cm.sup.2
(irradiation intensity of 10 mW/cm.sup.2 for an irradiation time of
10 seconds) or more under a nitrogen atmosphere to polymerize the
polymerizable liquid crystal compound in the liquid crystal
composition. Thus, cured liquid-crystal molecules were formed. As a
result, a homogeneously oriented optically anisotropic layer having
a dried thickness of 1.1 .mu.m was obtained, and a multilayer film
having a layer structure of (first substrate)/(optically
anisotropic layer) was obtained.
[0370] (1-4. Evaluation)
[0371] For the optically anisotropic layer of the obtained
multilayer film, the in-plane retardation and the angle formed
between the slow axis and the lengthwise direction were measured,
and the orientation state, the orientation defects, as well as a
bright spot and a heterogeneous matter were evaluated.
Example 2
[0372] A first substrate and a multilayer film were obtained by the
same operation as in Example 1 except for the following:
[0373] The thickness of the liquid crystal composition to be
applied in (1-2) was changed and the dried thickness of the
optically anisotropic layer obtained in (1-3) was changed to 2.0
.mu.m.
Example 3
[0374] A first substrate and a multilayer film were obtained by the
same operation as in Example 1 except for the following:
[0375] The stretching direction in (1-1) was changed to perform
diagonal stretching such that the slow axis of the substrate film
is formed at an angle of 22.5.degree. relative to the widthwise
direction (67.5.degree. relative to the lengthwise direction).
[0376] The liquid crystal composition (B) obtained in Production
Example 5 was used in place of the liquid crystal composition (A)
in (1-2); the temperature of the orientation treatment was changed
to 115.degree. C.
[0377] The thickness of the liquid crystal composition to be
applied in (1-2) was changed and the dried thickness of the
optically anisotropic layer obtained in (1-3) was changed to
2.2
Example 4
[0378] A first substrate and a multilayer film were obtained by the
same operation as in Example 1 except for the following:
[0379] The stretching direction in (1-1) was changed to perform
diagonal stretching such that the slow axis of the substrate film
is formed at an angle of 45.degree. relative to the widthwise
direction (45.degree. relative to the lengthwise direction).
Example 5
[0380] A first substrate and a multilayer film were obtained by the
same operation as in Example 1 except for the following:
[0381] The stretching direction in (1-1) was changed to perform
diagonal stretching such that the slow axis of the substrate film
is formed at an angle of 45.degree. relative to the widthwise
direction (45.degree. relative to the lengthwise direction).
[0382] The liquid crystal composition (B) obtained in Production
Example 5 was used in place of the liquid crystal composition (A)
in (1-2); the temperature of the orientation treatment was changed
to 115.degree. C.
[0383] The thickness of the liquid crystal composition to be
applied in (1-2) was changed and the dried thickness of the
optically anisotropic layer obtained in (1-3) was changed to
2.1
Example 6
[0384] A first substrate and a multilayer film were obtained by the
same operation as in Example 1 except for the following:
[0385] The pre-stretch substrate (C) obtained in Production Example
3 was used in place of the liquid crystal composition (A) in
(1-1).
[0386] The stretching direction in (1-1) was changed to perform
diagonal stretching such that the slow axis of the substrate film
is formed at an angle of 45.degree. relative to the widthwise
direction (45.degree. relative to the lengthwise direction).
[0387] The liquid crystal composition (B) obtained in Production
Example 5 was used in place of the liquid crystal composition (A)
in (1-2); the temperature of the orientation treatment was changed
to 115.degree. C.
[0388] The thickness of the liquid crystal composition to be
applied in (1-2) was changed and the dried thickness of the
optically anisotropic layer obtained in (1-3) was changed to
2.2
Example 7
[0389] A first substrate and a multilayer film were obtained by the
same operation as in Example 1 except for the following:
[0390] The pre-stretch substrate (B) obtained in Production Example
2 was used in place of the liquid crystal composition (A) in
(1-1).
[0391] The stretching direction in (1-1) was changed to perform
widthwise stretching such that the slow axis of the substrate film
is formed at an angle of 0.degree. relative to the widthwise
direction (90.degree. relative to the lengthwise direction).
Example 8
[0392] A first substrate and a multilayer film were obtained by the
same operation as in Example 1 except for the following:
[0393] A long-length triacetylcellulose (TAC) film (available from
Konica Minolta, Inc., thickness: 80 .mu.m, width: 1,490 mm, glass
transition temperature: 107.degree. C.) was used in place of the
pre-stretch substrate (A) in (1-1).
[0394] The stretching direction in (1-1) was changed to perform
diagonal stretching such that the slow axis of the substrate film
is formed at an angle of 45.degree. relative to the widthwise
direction (45.degree. relative to the lengthwise direction).
[0395] The temperature of the orientation treatment was decreased
to 90.degree. C. in (1-2) to avoid deformation of the TAC film.
Comparative Example 1
[0396] (C1-1. Preparation of Substrate having
Orientation-Controlling Force)
[0397] The pre-stretch substrate (A) was drawn from the roll of the
pre-stretch substrate (A) obtained in Production Example 1, the
masking film was continuously separated, and the pre-stretch
substrate (A) was supplied to a diagonal rubbing device, and rubbed
in a diagonal direction. The rubbing direction was adjusted to an
angle of the substrate film of 45.degree. relative to the widthwise
direction (45.degree. relative to the lengthwise direction).
[0398] After the rubbing treatment, both ends of the substrate film
in the widthwise direction of the substrate film were trimmed to
obtain a long-length substrate (A-3) having a width of 1,350 mm and
an orientation-controlling force. The Re of the obtained substrate
(A-3) was 5 nm and the film thickness thereof was 80 .mu.m. The
obtained substrate (A-3) was wound while a rubbed face was
protected with a new masking film (FF1025 available from Tredegar
Corporation). Thus, a roll of the substrate (A-3) was obtained.
[0399] (C1-2. Formation of Layer of Liquid Crystal Composition,
Orientation Treatment, Polymerization, and Evaluation)
[0400] A multilayer film was obtained and evaluated in the same
manner as in (1-2) to (1-4) of Example 1 except that the substrate
(A-3) obtained in (C1-1) was used in place of the first substrate
(A-1).
[0401] The results in Examples 1 to 10 and Comparative Example 1
are shown in Tables 1 and 2.
TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
Substrate type (A) (A) (A) (A) (A) (C) Substrate Diagonal Diagonal
Diagonal Diagonal Diagonal Diagonal stretch Substrate slow
15.degree. 15.degree. 22.5.degree. 45.degree. 45.degree. 45.degree.
axis direction Substrate 265 265 325 70 70 141 Re (nm) Substrate 40
40 75 75 75 60 thickness (.mu.m) Substrate .DELTA.n 0.006625
0.006625 0.004333 0.000933 0.000933 0.002350 Liquid crystal A A B A
B B type Orientation 110 110 115 110 115 115 temperature (.degree.
C.) Anisotropic 145 270 148 145 147 148 layer Re (nm) Anisotropic
1.1 2.0 2.2 1.1 2.1 2.2 layer thickness (.mu.m) Angle between
75.degree. 75.degree. 67.5.degree. 45.degree. 45.degree. 45.degree.
anisotropic layer slow axis and lengthwise direction Orientation
Excellent Excellent Good Excellent Good Good state Orientation Good
Good Good Good Good Good defects Bright spot Good Good Good Good
Good Good and heterogeneous matter
TABLE-US-00002 TABLE 2 Ex. 7 Ex. 8 Comp. Ex. 1 Substrate type (B)
TAC (A) Substrate Widthwise Diagonal No stretching stretch
(rubbing) Substrate slow 0.degree. 45.degree. 45 axis direction
Substrate 120 14 5 Re (nm) Substrate 40 79 80 thickness (.mu.m)
Substrate .DELTA.n 0.003000 0.0001770 -- Liquid crystal A A A type
Orientation 110 90 110 temperature (.degree. C.) Anisotropic 144
145 142 layer Re (nm) Anisotropic 1.1 1.1 1.1 layer thickness
(.mu.m) Angle between 90.degree. 45.degree. 45.degree. anisotropic
layer slow axis and lengthwise direction Orientation Good Good Good
state Orientation Good Good Good defects Bright spot Good Good Bad
and (heterogeneous) heterogeneous matter
Example 9
[0402] (9-1. Manufacturing of Circular Polarizing Plate)
[0403] A circular polarizing plate was manufactured using the
optically anisotropic layer of the multilayer film obtained in
Example 6 as a .lamda./4 wave plate.
[0404] As a long-length linear polarizer, a polarizing film
(product name "HLC2-5618S" available from Sanritz Corporation,
thickness: 180 .mu.m, transmission axis at an angle of 90.degree.
relative to the lengthwise direction (at an angle of 0.degree.
relative to the widthwise direction) was prepared. One face of the
film was attached to one face of the multilayer film obtained in
Example 6 on a side of the optically anisotropic layer (that is,
the .lamda./4 wave plate). The attachment was performed through an
adhesive layer (product name "CS9621" available from Nitto Denko
Corporation). Thus, a laminate (9-i) having a layer structure of
(polarizer)/(adhesive layer)/(.lamda./4 wave plate)/(first
substrate) was obtained.
[0405] The first substrate was then separated from the laminate
(9-i) to obtain a circular polarizing plate having a layer
structure of (polarizer)/(adhesive layer)/(.lamda./4 wave
plate).
[0406] Both the attachment and separation operations were
continuously performed by a roll-to-roll process. Therefore, the
attachment operation was performed in a state where the lengthwise
directions of the long-length films were aligned.
[0407] The optical axes of the components of the obtained circular
polarizing plate had the following angle relationship. That is,
when the circular polarizing plate was observed from a face on a
side of the polarizer, the slow axis of the .lamda./4 wave plate
was shifted clockwise at 45.degree. from the direction of
transmission axis of the polarizing plate.
[0408] (9-2. Evaluation)
[0409] The long-length circular polarizing plate obtained in (9-1)
was cut into an appropriate size, and evaluated by visual
observation.
[0410] Further, the face of the circular polarizing plate on the
side of the .lamda./4 wave plate was attached to a reflection face
of a reflection plate (product name: "Metalumy TS50" available from
Toray Industries, Inc., aluminum-deposited polyethylene
terephthalate (PET) film). The attachment was performed through an
adhesive layer (product name "CS9621" available from Nitto Denko
Corporation). Thus, a laminate (9-v) for evaluation having a layer
structure of (polarizer)/(adhesive layer)/(.lamda./4 wave
plate)/(adhesive layer)/(reflection plate) was obtained.
[0411] For the obtained laminate (9-v) for evaluation, the
reflectance of light incident on the face on the polarizer side was
measured. In the measurement, a spectrophotometer V7200 and an
absolute reflectance unit VRA7020 (manufactured by JASCO
Corporation) were used. In the measurement, the polar angle was
variously changed within a range of 5.degree. to 60.degree.. When
the circular polarizing plate was observed from the face on the
polarizer side, an azimuth angle was set to an angle of 0.degree.,
45.degree., 90.degree., and 135.degree. clockwise from the
direction of transmission axis of the polarizing plate. The results
are shown in FIG. 2.
Examples 10 to 12
[0412] A circular polarizing plate was obtained by the same
operation as in (9-1) of Example 9 except that the multilayer film
obtained in Example 4 (Example 10), the multilayer film obtained in
Example 5 (Example 11), or the multilayer film obtained in Example
8 (Example 12) was used in place of the multilayer film obtained in
Example 6.
[0413] The angle relationship of optical axes of the components of
the obtained circular polarizing plate was the same as that of the
circular polarizing plate obtained in Example 9.
[0414] The long-length circular polarizing plate obtained was cut
into an appropriate size, and evaluated by visual observation.
[0415] The evaluation results by visual observation in Examples 9
to 12 are shown in Table 3.
TABLE-US-00003 TABLE 3 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Example
manufacturing Ex. 6 Ex. 4 Ex. 5 Ex. 8 optically anisotropic layer
used Front contrast A B A B Viewing angle B B B B
characteristics
[0416] As clearly shown from the results of Tables 1 to 3, in
Examples of the present application, a multilayer film having a
reduced number of defects due to generation of a heterogeneous
matter was successfully manufactured, and a circular polarizing
plate having favorable performance was successfully manufactured
using the multilayer film.
Measurement Methods in Reference Examples 1 to 6 and Reference
Comparative Example 1
[0417] [1. Shift between Orientation Direction of Liquid Crystal
Resin Film and Slow Axis Direction of Substrate]
[0418] Before the liquid crystal composition was applied onto the
substrate, a reference line was drawn on a face of the substrate
opposite to a face onto which the liquid crystal composition was
applied. A layer of liquid crystal resin film was formed, and a
reference line was then drawn on a face of the liquid crystal resin
film at a position that corresponded to a reference plane of the
substrate. After that, the liquid crystal resin film was
transferred to a glass plate through an adhesive, and separated
from the substrate. The slow axis direction of the substrate and
the orientation direction of the liquid crystal resin film were
each measured by AxoScan (manufactured by Axometrics, Inc.). The
angle formed between the slow axis of the substrate and the
reference line on the substrate, and the angle formed between the
orientation direction of the liquid crystal resin film and the
reference line on the liquid crystal resin film were determined.
From the angles, a shift between the orientation direction of the
liquid crystal resin film and the slow axis direction of the
substrate was determined.
[0419] [2. Orientation Degree of Liquid Crystal Resin Film]
[0420] The liquid crystal resin film transferred to a glass plate
was disposed between a polarizer and an analyzer, and the
transmittance under crossed Nicols was measured by V7200 and
VAP-7070S manufactured by JASCO Corporation, and evaluated in
accordance with the following criteria.
[0421] Excellent: the transmittance under crossed Nicols at the
bottom wavelength was 0.010% or less.
[0422] Good: the transmittance under crossed Nicols at the bottom
wavelength was more than 0.010% and 0.020% or less.
[0423] Passable: the transmittance under crossed Nicols at the
bottom wavelength was more than 0.020% and 0.030% or less.
[0424] [3. Amount of Heterogeneous Matter]
[0425] The liquid crystal resin film was visually observed, and the
amount of heterogeneous matters per square meter was counted, and
evaluated in accordance with the following criteria.
[0426] Good: the number of heterogeneous matters per square meter
was 5 or less.
[0427] Bad: the number of heterogeneous matters per square meter
was 6 or more.
Reference Example 1
[0428] (Step (1-1): Preparation of Pre-Stretch Substrate of Resin
having Alicyclic Structure)
[0429] Pellets of a thermoplastic norbornene resin (product name
"ZEONOR1420R" available from ZEON CORPORATION) were dried at
90.degree. C. for 5 hours. The dried pellets were supplied to an
extruder, melted in the extruder, passed through a polymer pipe and
a polymer filter, and extruded from a T-die on a casting drum to be
in a sheet shape. The sheet was cooled, and wound to obtain a roll
of pre-stretch substrate having a thickness of 80 .mu.m and a width
of 1,490 mm.
[0430] (Step (1-2): Preparation of Stretched Substrate of Resin
having Alicyclic Structure)
[0431] The pre-stretch substrate obtained in (1-1) was drawn from
the roll, supplied to a tenter stretching machine, and stretched
such that the orientation angle of the film is set at 45.degree.
relative to the winding direction of the film. Both ends in the
widthwise direction of the film were trimmed, and the film was
wound to obtain a roll of long-length stretched substrate having a
width of 1,350 mm. The Re of the resulting stretched substrate was
69.3 nm and the film thickness was 75 The value of .DELTA.n
calculated by (Re(nm))/(film thickness (.mu.m).times.1,000) was
0.000923.
[0432] (Step (1-3): Preparation of Liquid Crystal Composition)
[0433] 21.25 parts of a polymerizable liquid crystal compound
having inverse wavelength distribution represented by a formula
(B1) of Production Example 5, 0.11 parts of a surfactant (product
name "Surflon 5420" available from AGC Seimi Chemical Co., Ltd.),
0.64 parts of a polymerization initiator (product name
"IRGACURE379" available from BASF), and 78.00 parts of a solvent
(cyclopentanone available from ZEON CORPORATION) were mixed to
prepare a liquid crystal composition.
[0434] (Step (1-4): Formation of Liquid Crystal Resin Film)
[0435] The stretched substrate prepared in Step (1-2) was drawn
from the roll, and conveyed, and the liquid crystal composition
prepared in Step (1-3) was applied onto one surface of the
substrate by a die coater to form a layer of the liquid crystal
composition. The layer of the liquid crystal composition was
subjected to an orientation treatment at 110.degree. C. for 2.5
minutes, and irradiated with ultraviolet light having 100
mJ/cm.sup.2 or more under an N.sub.2 atmosphere, to obtain a layer
of a liquid crystal resin film having a dried thickness of 2 .mu.m
and containing cured liquid-crystal molecules homogeneously
oriented. For confirmation of homogeneous orientation, AxoScan
(manufactured by Axometrics, Inc.) was used. The slow axis
direction of the liquid crystal resin film layer was measured, and
Re's in various incidence angles in the slow axis direction at
every 10.degree. within a range of incidence angle of -70.degree.
to 70.degree. were measured. A measurement wavelength of 550 nm was
used. When Re at a negative incidence angle and Re at a positive
incidence angle are approximately symmetric about an incidence
angle of 0.degree. as the center, it can be said that homogeneous
orientation is achieved. Re's of the obtained liquid crystal resin
film at every incidence angle had a symmetry about 0.degree. as the
center, and homogeneous orientation was thus confirmed.
[0436] (Step (1-5): Evaluation)
[0437] The shift between the orientation direction of the liquid
crystal resin film obtained in Step (1-4) and the slow axis
direction of the substrate was less than 1.degree.. The orientation
degree of the obtained liquid crystal resin film and the amount of
a heterogeneous matter were evaluated. The results are shown in
Table 5.
Reference Examples 2 and 3
[0438] A stretched substrate, a liquid crystal composition, and a
liquid crystal resin film were obtained and evaluated in the same
manner as in Reference Example 1 except that the types and ratios
of components constituting the liquid crystal composition were
changed as shown in Table 4, the conditions for stretching an
pre-stretch substrate was changed, and a stretched substrate having
a different value .DELTA.n was used. The results are shown in Table
5. In all Reference Examples, the shift between the orientation
direction of the liquid crystal resin film and the slow axis
direction of the substrate was less than 1.degree..
Reference Example 4
[0439] (Step (4-1): Preparation of Triacetylcellulose Stretched
Substrate)
[0440] A roll of a long-length triacetylcellulose film (available
from Konica Minolta, Inc., thickness: 80 .mu.m, width: 1,490 mm)
was prepared as an pre-stretch substrate. The pre-stretch substrate
was drawn from the roll, supplied to a tenter stretching machine,
and stretched at a stretching temperature of 155.degree. C. and a
stretching ratio of 1.01, such that the orientation angle of the
film is set at 45.degree. relative to the winding direction. Both
ends in the widthwise direction of the film were trimmed, and the
film was wound to obtain a roll of long-length stretched substrate
having a width of 1,350 mm. The Re of the resulting stretched
substrate was 14 nm and the film thickness was 79 The value of
.DELTA.n calculated by (Re(nm))/(film thickness
(.mu.m).times.1,000) was 0.000078.
[0441] (Step (4-2): Preparation of Liquid Crystal Composition)
[0442] 24.15 parts of a polymerizable liquid crystal compound
(product name "LC242" available from BASF, a compound represented
by a formula (Al) in Production Example 4), 0.12 parts of a
surfactant (product name "FTERGENT FTX-209F" available from Neos
Company Limited), 0.73 parts of a polymerization initiator (product
name "IRGACURE379" available from BASF), and 75.00 parts of a
solvent (cyclopentyl methyl ether available from ZEON CORPORATION)
were mixed to prepare a liquid crystal composition.
[0443] (Step (4-3): Formation of Liquid Crystal Resin Film)
[0444] The stretched substrate prepared in Step (4-1) was drawn
from the roll, and conveyed, and the liquid crystal composition
prepared in Step (4-2) was applied onto one surface of the
substrate by a die coater to form a layer of the liquid crystal
composition. The layer of the liquid crystal composition was
subjected to an orientation treatment at 110.degree. C. for 2.5
minutes, and irradiated with ultraviolet light having 100
mJ/cm.sup.2 or more under an N.sub.2 atmosphere, to obtain a layer
of a liquid crystal resin film having a dried thickness of 2 .mu.m
and being homogeneously oriented. The homogeneous orientation was
confirmed by the same method as the confirmation method in Step
(1-4) of Reference Example 1.
[0445] (Step (4-4): Evaluation)
[0446] The shift between the orientation direction of the liquid
crystal resin film obtained in Step (4-3) and the slow axis
direction of the substrate was less than 1.degree.. The orientation
degree of the obtained liquid crystal resin film and the amount of
a heterogeneous matter were evaluated. The results are shown in
Table 5.
Reference Examples 5 and 6
[0447] A stretched substrate, a liquid crystal composition, and a
liquid crystal resin film were obtained and evaluated in the same
manner as in Reference Example 4 except that the types and ratios
of components constituting the liquid crystal composition were
changed as shown in Table 4, and the conditions for stretching an
pre-stretch substrate was changed as shown in Table 5. The results
are shown in Table 5. In both Reference Examples, the shift between
the orientation direction of the liquid crystal resin film and the
slow axis direction of the substrate was less than 1.degree..
Reference Comparative Examples 1
[0448] The pre-stretch substrate obtained in Step (1-1) of
Reference Example 1 was drawn from the roll, and rubbed in an MD
direction. The liquid crystal composition having the same
composition as that used in Reference Example 2 was applied onto
one surface of the substrate by a die coater to form a layer of the
liquid crystal composition. The layer of the liquid crystal
composition was subjected to an orientation treatment at
110.degree. C. for 2.5 minutes, and irradiated with ultraviolet
light having 100 mJ/cm.sup.2 or more under an N.sub.2 atmosphere,
to obtain a layer of a liquid crystal resin film having a dried
thickness of 2 .mu.m and being homogeneously oriented. The
homogeneous orientation was confirmed by the same method as the
confirmation method in Step (1-4) of Reference Example 1. The shift
between the orientation direction of the obtained liquid crystal
resin film and the slow axis direction of the substrate was less
than 1.degree.. The orientation degree of the obtained liquid
crystal resin film and the amount of a heterogeneous matter were
evaluated. The results are shown in Table 5.
TABLE-US-00004 TABLE 4 Ref. Comp. Ref. Ex. 1 Ref. Ex. 2 Ref. Ex. 3
Ref. Ex. 4 Ref. Ex. 5 Ref. Ex. 6 Ex. 1 Liquid crystal Inverse LC242
Inverse LC242 LC242 Inverse LC242 compound wavelength wavelength
wavelength Amount (parts) 21.25 24.15 21.25 24.15 24.15 21.25 24.15
Surfactant S420 209F S420 209F 209F S420 209F Amount (parts) 0.11
0.12 0.11 0.12 0.12 0.11 0.12 Polymerization Irg379 Irg379 Irg379
Irg379 Irg379 Irg379 Irg379 initiator Amount (parts) 0.64 0.73 0.64
0.73 0.73 0.64 0.73 Solvent CPN CPN CPN CPME CPME CPME CPN Amount
(parts) 78.00 75.00 78.00 75.00 75.00 78.00 75.00
TABLE-US-00005 TABLE 5 Orientation Slow axis Liquid Substrate
Heterogeneous control direction crystal Substrate Re thickness
Orientation Orientation matter Substrate method (.degree.) .DELTA.n
material (nm) (.mu.m) state degree amount Ref. COP Diagonal 45
0.000923 Inverse 69.3 75 Homogeneous Good Good Ex. 1 wavelength
Ref. COP Diagonal 45 0.001607 LC242 91.6 57 Homogeneous Excellent
Good Ex. 2 Ref. COP Diagonal 22.5 0.006397 Inverse 280 44
Homogeneous Excellent Good Ex. 3 wavelength Ref. TAC Diagonal 45
0.000078 LC242 14 79 Homogeneous Passable Good Ex. 4 Ref. TAC
Diagonal 45 0.000124 LC242 6 77 Homogeneous Good Good Ex. 5 Ref.
TAC Diagonal 45 0.000175 Inverse 9.3 75 Homogeneous Good Good Ex. 6
wavelength Ref. COP Rubbing (MD) -- LC242 -- Homogeneous Good Bad
Comp. Ex. 1
[0449] Meanings of the abbreviations in Tables 4 and 5 are as
follows.
[0450] Inverse wavelength: polymerizable liquid crystal compound
having inverse wavelength distribution represented by the
aforementioned formula (B1)
[0451] LC242: polymerizable liquid crystal compound (product name
"LC242" available from BASF, a compound represented by the
aforementioned formula (A1))
[0452] S420: surfactant (product name "Surflon 5420" available from
AGC Seimi Chemical Co., Ltd.)
[0453] 209F: surfactant (product name "FTERGENT FTX-209F" available
from Neos Company Limited)
[0454] Irg379: polymerization initiator (product name "IRGACURE379"
available from BASF)
[0455] CPN: cyclopentanone available from ZEON CORPORATION CPME:
cyclopentyl methyl ether available from ZEON CORPORATION
[0456] COP: resin having an alicyclic structure (thermoplastic
norbornene resin, product name "ZEONOR1420R" available from ZEON
CORPORATION)
[0457] TAC: triacetylcellulose film (available from Konica Minolta,
Inc.)
[0458] As clear from the results in Tables 4 and 5, the liquid
crystal resin films of Reference Examples 1 to 6 were good films
that had favorable orientation in a diagonal direction and a
smaller amount of heterogeneous matters than that in Reference
Comparative Example 1.
* * * * *