U.S. patent application number 09/756730 was filed with the patent office on 2001-07-19 for norbornene based resin composition and phase difference plate.
Invention is credited to Arakawa, Kohei.
Application Number | 20010008920 09/756730 |
Document ID | / |
Family ID | 18534113 |
Filed Date | 2001-07-19 |
United States Patent
Application |
20010008920 |
Kind Code |
A1 |
Arakawa, Kohei |
July 19, 2001 |
Norbornene based resin composition and phase difference plate
Abstract
A phase difference plate is provided which can be formed by a
single material at a low cost without a need for forming laminated
layers, and which has excellent performance in a wide band. The
phase difference plate is formed by using a norbornene based resin
composition which includes a norbornene based resin; and a polymer
whose birefringence value is negative, and whose wavelength
dispersion of birefringence values satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vertline..gtoreq.1- .02,
wherein .DELTA.n(450) and .DELTA.n(550) are birefringence values
(.DELTA.n) at a wavelength of 450 nm and a wavelength of 550 nm,
respectively. The polymer is preferably a polystyrene based
polymer.
Inventors: |
Arakawa, Kohei; (Kanagawa,
JP) |
Correspondence
Address: |
BURNS DOANE SWECKER & MATHIS L L P
POST OFFICE BOX 1404
ALEXANDRIA
VA
22313-1404
US
|
Family ID: |
18534113 |
Appl. No.: |
09/756730 |
Filed: |
January 10, 2001 |
Current U.S.
Class: |
525/210 |
Current CPC
Class: |
C08L 45/00 20130101;
C08L 25/06 20130101; C08L 45/00 20130101; C08L 35/06 20130101; C08L
2666/02 20130101 |
Class at
Publication: |
525/210 |
International
Class: |
C08L 045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2000 |
JP |
2000-5446 |
Claims
What is claimed is:
1. A norbornene based resin composition comprising: a norbornene
based resin; and a polymer whose birefringence value is negative,
and whose wavelength dispersion of birefringence values satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vertline..gtoreq.1.02,
wherein .DELTA.n(450) and .DELTA.n(550) are birefringence values
(.DELTA.n) at a wavelength of 450 nm and a wavelength of 550 nm,
respectively.
2. A norbornene based resin composition according to claim 1,
wherein the norbornene based resin is a thermoplastic norbornene
resin.
3. A norbornene based resin composition according to claim 2,
wherein the thermoplastic norbornene resin has a repeating unit
expressed by any of following structural formulas (I) through (IV).
3
4. A norbornene based resin composition according to claim 2,
wherein the thermoplastic norbornene resin is a water-added
polymer, which is obtained by the hydrogen addition of a polymer
obtained by metathesis polymerization of at least one type of
tetracyclododecene expressed by following structural formula (V)
and an unsaturated cyclic compound which is polymerizable
therewith. 4
5. A norbornene based resin composition according to claim 1,
wherein a weight average molecular weight of the norbornene based
resin is 5,000 to 1,000,000.
6. A norbornene based resin composition according to claim 1,
wherein the wavelength dispersion of birefringence values of the
polymer satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vertline..gtoreq.1.05,
wherein .DELTA.n(450) and .DELTA.n(550) are birefringence values
(.DELTA.n) at a wavelength of 450 nm and a wavelength of 550 nm,
respectively.
7. A norbornene based resin composition according to claim 1,
wherein the polymer is a polystyrene based polymer.
8. A norbornene based resin composition according to claim 1,
wherein a weight ratio of the norbornene based resin and the
polymer whose birefringence value is negative (the norbornene based
resin:the polymer whose birefringence value is negative) is 5:5 to
9:1.
9. A norbornene based resin composition according to claim 1,
wherein the norbornene based resin composition is used in a phase
difference plate having birefringence.
10. A phase difference plate formed by using a norbornene based
resin composition comprising: a norbornene based resin; and a
polymer whose birefringence value is negative, and whose wavelength
dispersion of birefringence values satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vert- line..gtoreq.1.02,
wherein .DELTA.n(450) and .DELTA.n(550) are birefringence values
(.DELTA.n) at a wavelength of 450 nm and a wavelength of 550 nm,
respectively.
11. A phase difference plate according to claim 10, wherein the
phase difference plate satisfies Re(450 nm)<Re(550 nm)<Re(650
nm), wherein Re(450 nm), Re(550 nm), and Re(650 nm) are retardation
(Re) values at wavelengths of 450 nm, 550 nm, and 650 nm,
respectively.
12. A phase difference plate according to claim 10, wherein the
norbornene based resin is a thermoplastic norbornene resin.
13. A phase difference plate according to claim 12, wherein the
thermoplastic norbornene resin has a repeating unit expressed by
any of following structural formulas (I) through (IV). 5
14. A phase difference plate according to claim 12, wherein the
thermoplastic norbornene resin is a water-added polymer, which is
obtained by the hydrogen addition of a polymer obtained by
metathesis polymerization of at least one type of
tetracyclododecene expressed by following structural formula (V)
and an unsaturated cyclic compound which is polymerizable
therewith. 6
15. A phase difference plate according to claim 10, wherein a
weight average molecular weight of the norbornene based resin is
5,000 to 1,000,000.
16. A phase difference plate according to claim 10, wherein the
wavelength dispersion of birefringence values of the polymer
satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vertline..gtoreq.1.05,
wherein .DELTA.n(450) and .DELTA.n(550) are birefringence values
(.DELTA.n) at a wavelength of 450 nm and a wavelength of 550 nm,
respectively.
17. A phase difference plate according to claim 10, wherein the
polymer is a polystyrene based polymer.
18. A phase difference plate according to claim 10, wherein a
weight ratio of the norbornene based resin and the polymer whose
birefringence value is negative (the norbornene based resin:the
polymer whose birefringence value is negative) is 5:5 to 9:1.
19. A phase difference plate according to claim 10, wherein the
phase difference plate is one of a wide band .lambda./4 plate and a
wide band .lambda./2 plate.
20. A phase difference plate according to claim 10, wherein the
phase difference plate is used in a liquid crystal display device.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a phase difference plate
which is suitable for a reflection-type liquid crystal display
device which can be used as a display device in various fields such
as personal computers, AV equipment, portable information
communication devices, game and simulation devices, on-board
navigation systems, and the like, and to a norbornene based resin
composition which is suitably used in the phase difference
plate.
[0003] 2. Description of the Related Art
[0004] A .lambda./4 plate, whose retardation (Re) is 1/4of the
length of a wavelength, has various applications in reflection-type
LCDs, pick-up for optical discs, anti-glare films, and the like. A
.lambda./2 plate, whose retardation (Re) is 1/2of the length of a
wavelength, is useful as a liquid crystal projector. In each of
these applications, it is preferable that the .lambda./4 plate and
the .lambda./2 plate sufficiently exhibit functions with respect to
all of the incident light in the range of visible light which can
be seen by the human eye.
[0005] For example, Japanese Patent Application Laid-Open (JP-A)
Nos. 5-27118, 5-100114, 10-68816 and 10-90521 have proposed, as
wide band phase difference plates functioning as .lambda./4 plates
and .lambda./2 plates with respect to incident light in the entire
visible light region, structures in which two polymer films having
respective different optical anisotropy are layered.
[0006] However, in these cases, in the production thereof, it is
necessary to obtain two types of chips in which elongate films,
which are each drawn in one direction, are cut in directions
forming different angles with respect to the directions of drawing,
and to laminate these chips together. In such a .lambda./4 plate,
the optical anisotropy (inclination of the optical axis or the slow
axis) of each polymer film is determined by the angle at which the
chip is cut with respect to the direction of drawing of the drawn
film. Thus, a precise cutting technology is required. Moreover,
when the two chips are laminated, an adhesive must be applied and
precise alignment must be carried out, such that the production
processes are complex. Namely, processes such as an adhering
process, a chip-forming process, a laminating process, and the like
result in an increase in costs. Further, dirtying caused by the
scum produced during chip-forming and the like, dispersion in the
phase differences caused by errors in the laminating angle, and the
like adversely affect the actual performances.
[0007] Currently, there has not yet been provided a technology in
which a wide band .lambda./4 plate or a wide band .lambda./2 plate,
which has retardation of 1/4wavelength or 1/2wavelength in the
entire region of visible light and which is sufficiently durable to
be able to withstand use, is formed by a single material without
forming layers.
SUMMARY OF THE INVENTION
[0008] An object of the present invention is to provide a phase
difference plate which can be formed by a single material at a low
cost without having to form a laminated structure, and which
exhibits excellent performances in a wide band. Moreover, an object
of the present invention is to provide a norbornene based resin
composition which is suitably used in the phase difference
plate.
[0009] The norbornene based resin composition of the present
invention comprises: a norbornene based resin; and a polymer whose
birefringence value is negative, and whose wavelength dispersion of
birefringence values satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vertline..gtoreq.1- .02,
wherein .DELTA.n(450) and .DELTA.n(550) are birefringence values
(.DELTA.n) at a wavelength of 450 nm and a wavelength of 550 nm,
respectively.
[0010] The phase difference plate of the present invention is
formed by using the norbornene based resin composition of the
present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a graph showing results of measurement of
wavelength dispersion characteristics of Re values in a visible
light range of phase difference plates manufactured in Example 1,
Comparative Example 1, and Comparative Example 2.
[0012] FIG. 2 is a graph showing results of measurement of
wavelength dispersion characteristics of Re values in a visible
light range of phase difference plates manufactured in Example 2,
Comparative Example 3 and Comparative Example 4.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Norbornene Based Resin Composition
[0013] The norbornene based resin composition of the present
invention comprises a norbornene based resin and a polymer whose
birefringence value is negative, as well as other components which
are appropriately selected as needed.
Norbornene Based Resin
[0014] The norbornene based resin has the characteristic of
exhibiting positive optical uniaxiality when the molecules are
oriented in uniaxial order.
[0015] The norbornene based resin is not particularly limited, and
can be appropriately selected in accordance with the object.
However, thermoplastic norbornene resins are preferable from the
standpoints of excellent transparence, low water absorbency,
excellent heat-resistance, low photoelasticity, and their suitably
to optical applications.
[0016] The thermoplastic norbornene resin has, as the repeating
unit thereof, a norbornene skeleton. Specific examples thereof are
disclosed in JP-A-60-168708, 62-252406, 62-252407, 2-133413,
63-145324, 63-264626, 1-240517, Japanese Patent Application
Publication (JP-B) No. 57-8815, and the like. One type of
thermoplastic norbornene resin may be used alone, or two or more
types may be used in combination.
[0017] In the present invention, among the thermoplastic norbornene
resins, those having a repeating unit expressed by any of following
structural formulas (I) through (IV) are preferable. 1
[0018] In the above structural formulas, A, B, C and D represent a
hydrogen atom or a monovalent organic group.
[0019] Among the thermoplastic norbornene resins, a hydrogen-added
polymer, which is obtained by the hydrogen addition of a polymer
obtained by metathesis polymerization of at least one type of
tetracyclododecene expressed by following structural formula (V)
and an unsaturated cyclic compound which is polymerizable
therewith; is preferable. 2
[0020] In the above structural formula, A, B, C and D represent a
hydrogen atom or a monovalent organic group.
[0021] The weight average molecular weight of the norbornene based
resin is around 5,000 to 1,000,000, and is preferably 8,000 to
200,000.
Polymer whose Birefringence Value is Negative
[0022] The polymer whose birefringence value is negative is a
polymer in which, when the molecules thereof are oriented in order
uniaxially, the overall optical characteristic of the polymer
exhibits negative uniaxiality.
[0023] The polymer whose birefringence value is negative may be a
single polymer exhibiting such a characteristic, or a polymer
having such a characteristic may be obtained by blending two or
more polymers.
[0024] The polymer whose birefringence value is negative is
selected from polymers in which the wavelength dispersion of the
birefringence value is large. Specifically, the polymer is selected
from polymers whose wavelength dispersion of the birefringence
value satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vertline..gtoreq.1.02, and
preferably satisfies
.vertline..DELTA.n(450)/.DELTA.n(550).vertline..gtor- eq.1.05,
wherein the birefringence values (.DELTA.n) at a wavelength of 450
nm and a wavelength of 550 nm are .DELTA.n(450) and .DELTA.n(550),
respectively.
[0025] Further, the larger the value of
.vertline..DELTA.n(450)/.DELTA.n(5- 50).vertline., the better.
However, in the case of polymers,
.vertline..DELTA.n(450)/.DELTA.n(550).vertline. is usually 2.0 or
less.
[0026] Examples of the polymers are polystyrene based polymers,
polyacrylonitrile based polymers, polymethylmethacrylate based
polymers, cellulose ester based polymers (excluding those having an
birefringence value which is positive), or copolymers (binary,
ternary, etc.) thereof. A single such polymer can be used alone, or
two or more types of such polymers can be used in combination.
[0027] Among these, polystyrene based polymers such as polystyrene,
styrene/acrylonitrile copolymers, styrene/maleic anhydride
copolymers, styrene/methylmethacrylate copolymers, and the like are
particularly preferable.
[0028] The mixing ratio of the polymer whose birefringence value is
negative with respect to the norbornene based resin differs in
accordance with the magnitudes of the absolute values of the
birefringence values of both, the manifestation of birefringence at
the molding temperature, and the like. Although the mixing ratio
cannot be unconditionally limited, the mixing ratio is preferably a
weight ratio (norbornene based resin:polymer having a negative
birefringence value) of 5:5 to 9:1, and more preferably 7:3 to
8:2.
Other Components
[0029] The other components are not particularly limited, provided
that they do not adversely affect the effects of the present
invention, and can be selected appropriately as needed. A suitable
example of such other components are compatibilizing agents.
[0030] A compatibilizing agent is suitably used in cases in which
phase separation occurs when the norbornene based resin and the
polymer whose birefringence value is negative are mixed together.
By using a compatibilizing agent, the mixed-together state of the
norbornene based resin and the birefringence value is
satisfactory.
Application
[0031] The norbornene based resin composition of the present
invention can be suitably used in a phase difference plate having
birefringence.
Phase Difference Plate
[0032] The phase difference plate of the present invention is
formed by using the norbornene based resin composition of the
present invention.
[0033] It is preferable that the phase difference plate satisfies
the inequality Re(450 nm)<Re(550 nm)<Re(650 nm), wherein
Re(450 nm), Re(550 nm), Re(650 nm) are the retardation (Re) values
at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
[0034] The phase difference plate is preferably either a wide band
.lambda./4 plate or a wide band .lambda./2 plate.
[0035] The method of manufacturing the phase difference plate of
the present invention is not particularly limited, and can be
selected appropriately in accordance with the object. For example,
the phase difference plate can be manufactured as follows. Namely,
the phase difference plate can be manufactured by a solution film
forming method in which the norbornene based resin composition of
the present invention is made into a solution and is applied and
dried so as to form a film. Or, the phase difference plate can be
manufactured by an extrusion molding method in which the norbornene
based resin composition of the present invention is made into
pellets which are melt extruded and form a film.
[0036] Given that Re(450 nm), Re(550 nm), Re(650 nm) are the
retardation (Re) values at wavelengths of 450 nm, 550 nm, and 650
nm, respectively, if the phase difference plate obtained as
described above satisfies the inequality Re(450 nm)<Re(550
nm)<Re(650 nm), it can be used as it is. However, if the phase
difference plate does not satisfy this inequality, it is preferable
that the phase difference plate is used after the retardation (Re)
values have been controlled to satisfy the above inequality, by
changing the conditions such as the compositional ratio, the
drawing temperature, or the like.
[0037] Preferable examples of the aforementioned drawing are
longitudinal uniaxial drawing for drawing in the direction of
mechanical flow, lateral uniaxial drawing (e.g., tenter drawing)
for drawing in the direction orthogonal to the direction of
mechanical flow, and the like. However, if there is anisotropy in
the drawing, biaxial drawing may be carried out.
Application
[0038] The phase difference plate of the present invention exhibits
desired characteristics with a single molded body. Thus, there is
no need to laminate two or more members, and the phase difference
plate can be manufactured at a low cost, and exhibits excellent
performances in a wide band. The phase difference plate of the
present invention is suitably used in reflective-type liquid
crystal display devices which can be used as display devices in
various fields such as personal computers, AV equipment, portable
information communications equipment, game and simulation devices,
on-board navigation systems, and the like.
[0039] Hereinafter, Examples of the present invention will be
described. However, it is to be noted that the present invention is
not limited to these Examples.
EXAMPLE 1
[0040] A coating solution (25 wt %) was prepared by dissolving, in
a methylene chloride solution, 19 parts by weight of a norbornene
resin (ATON F, manufactured by JSR Co.) as the norbornene based
resin, and 6 parts by weight of polystyrene (HRM-2-211L
manufactured by Toyo Styrene Co.) as the material whose
birefringence value is negative, and a small amount of a
compatibilizing agent (a copolymer of norbornene and styrene).
[0041] The aforementioned polystyrene had a wavelength dispersion
of the birefringence value of
.vertline..DELTA.n(450)/.DELTA.n(550).vertline.=1.- 05, wherein the
birefringence values (.DELTA.n) at wavelengths of 450 nm and 550 nm
were .DELTA.n(450) and .DELTA.n(550).
[0042] The above coating solution was flowingly spread onto a glass
plate by using a doctor blade and was dried so that a transparent
film having a thickness of 104 .mu.m was formed. The transparent
film was 23% uniaxially extruded at 150.degree. C. so as to obtain
a phase difference plate. The wavelength dispersion of the Re
values of the phase difference plate was measured by using a
retardation measuring device (KOBRA21DH, manufactured by Oji
Keisoku Co.). The results are shown in FIG. 1.
[0043] As can be seen in FIG. 1, the phase difference plate
satisfied the inequality Re(450 nm)<Re(550 nm)<Re(650 nm),
wherein Re(450 nm), Re(550 nm), Re(650 nm) are the retardation (Re)
values at wavelengths of 450 nm, 550 nm, and 650 nm, respectively.
The phase difference plate exhibited the characteristic of a
.lambda./4 plate in a wide band.
COMPARATIVE EXAMPLE 1
[0044] A phase difference wavelength plate was formed in the same
manner as in Example 1, except that polystyrene was not used, the
thickness of the transparent film was 105 .mu.m, and the
transparent film was 36% uniaxially extruded at 155.degree. C. The
wavelength dispersion of the Re values was measured in the same way
as in Example 1. The results are shown in FIG. 1.
[0045] As can be seen from FIG. 1, this phase difference plate did
not exhibit the characteristics of a wide band .lambda./4
plate.
COMPARATIVE EXAMPLE 2
[0046] A phase difference wavelength plate was formed in the same
manner as in Example 1, except that norbornene resin was not used,
the thickness of the transparent film was 97 .mu.m, and the
transparent film was 17% uniaxially extruded at 110.degree. C. The
wavelength dispersion of the Re values was measured in the same way
as in Example 1. The results are shown in FIG. 1.
[0047] As can be seen from FIG. 1, this phase difference plate did
not exhibit the characteristics of a wide band .lambda./4
plate.
EXAMPLE 2
[0048] A coating solution (25 wt %) was prepared by dissolving, in
a methylene chloride solution, 19 parts by weight of a norbornene
resin (ATON F, manufactured by JSR Co.) as the norbornene based
resin, and 6 parts by weight of polystyrene (HRM-2-211L
manufactured by Toyo Styrene Co.) as the material whose
birefringence value is negative, and a small amount of a
compatibilizing agent (a copolymer of norbornene and styrene).
[0049] The aforementioned polystyrene had a wavelength dispersion
of the birefringence values of
.vertline..DELTA.n(450)/.DELTA.n(550).vertline.=0- .82, wherein the
birefringence values (.DELTA.n) at wavelengths of 450 nm and 550 nm
were .DELTA.n(450) and .DELTA.n(550).
[0050] The above coating solution was flowingly spread onto a glass
plate by using a doctor blade and was dried so that a transparent
film having a thickness of 210 .mu.m was formed. The transparent
film was 23% uniaxially extruded at 150.degree. C. so as to obtain
a phase difference plate. The wavelength dispersion of the Re
values of the phase difference plate was measured by using a
retardation measuring device (KOBRA21DH, manufactured by Oji
Keisoku Co.). The results are shown in FIG. 2.
[0051] As can be seen in FIG. 2, the phase difference plate
satisfied the inequality Re(450 nm)<Re(550 nm)<Re(650 nm),
wherein Re(450 nm), Re(550 nm), and Re(650 nm) are the retardation
(Re) values at wavelengths of 450 nm, 550 nm, and 650 nm,
respectively. The phase difference plate exhibited the
characteristic of a .lambda./2 plate in a wide band.
COMPARATIVE EXAMPLE 3
[0052] A phase difference wavelength plate was formed in the same
manner as in Example 1, except that polystyrene was not used, the
thickness of the transparent film was 219 .mu.m, and the
transparent film was 35% uniaxially extruded at 155.degree. C. The
wavelength dispersion of the Re values was measured in the same way
as in Example 2. The results are shown in FIG. 2.
[0053] As can be seen from FIG. 2, this phase difference plate did
not exhibit the characteristics of a wide band .lambda./2
plate.
COMPARATIVE EXAMPLE 4
[0054] A phase difference wavelength plate was formed in the same
manner as in Example 2, except that norbornene resin was not used,
the thickness of the transparent film was 127 .mu.m, and the
transparent film was 24% uniaxially extruded at 110.degree. C. The
wavelength dispersion of the Re values was measured in the same way
as in Example 2. The results are shown in FIG. 2.
[0055] As can be seen from FIG. 2, this phase difference plate did
not exhibit the characteristics of a wide band .lambda./2
plate.
EXAMPLE 3
[0056] A coating solution (25 wt %) was prepared by dissolving, in
toluene, 16 parts by weight of a norbornene resin (ATON F,
manufactured by JSR Co.) as the norbornene based resin, and 9 parts
by weight of a styrene/maleic anhydride copolymer (DAIRAK 232,
manufactured by Sekisui Kagaku Co.) as the material whose
birefringence value is negative.
[0057] The aforementioned styrene/maleic anhydride copolymer had a
wavelength dispersion of the birefringence value of
.vertline..DELTA.n(450)/.DELTA.n(550).vertline. =1.06, wherein the
birefringence values (.DELTA.n) at wavelengths of 450 nm and 550 nm
were .DELTA.n(450) and .DELTA.n(550).
[0058] The above coating solution was flowingly spread onto a glass
plate by using a doctor blade and was dried so that a transparent
film having a thickness of 210 .mu.m was formed. The transparent
film was 23 % uniaxially extruded at 150.degree. C. so as to obtain
a phase difference plate. The wavelength dispersion of the Re
values of the phase difference plate was measured by using a
retardation measuring device (KOBRA21DH, manufactured by Oji
Keisoku Co.).
[0059] The results thereof were that the phase difference plate of
Example 3 satisfied the inequality Re(450 nm)<Re(550
nm)<Re(650 nm), wherein Re(450 nm), Re(550 nm), Re(650 nm) are
the retardation (Re) values at wavelengths of 450 nm, 550 nm, and
650 nm, respectively. The phase difference plate exhibited the
characteristic of a .lambda./4 plate in a wide band.
[0060] The present invention provides a phase difference plate
which overcomes the above-described drawbacks of the prior art, and
which can be formed from a single material at a low cost without
the need to form laminated layers, and which has excellent
performances in a wide band. The present invention also provides a
norbornene based resin composition which is suitably used in the
phase difference plate.
* * * * *