U.S. patent application number 10/207853 was filed with the patent office on 2003-04-03 for polarizer protection film.
This patent application is currently assigned to Sekisui Chemical Co., Ltd.. Invention is credited to Hiratani, Kazuaki, Kobayashi, Hitoshi, Nozato, Shoji, Okada, Yasumasa, Otsuki, Toshihiro, Sawada, Takahiko.
Application Number | 20030063237 10/207853 |
Document ID | / |
Family ID | 19062905 |
Filed Date | 2003-04-03 |
United States Patent
Application |
20030063237 |
Kind Code |
A1 |
Okada, Yasumasa ; et
al. |
April 3, 2003 |
Polarizer protection film
Abstract
A polarizer protection film for protecting a polarizer used in a
liquid crystal display is obtained by using a film obtained by melt
film formation of a norbornene resin having a glass transition
temperature Tg of 135.degree. C. to 180.degree. C., and an inherent
viscosity (.eta..sub.inh) of 0.4 or more, measured at 30.degree.
C., in chloroform, wherein the Tg and .eta..sub.inh are within the
range indicated by the following equation (2):
45.eta..sub.inh.ltoreq.58.5-0.2T (2)
Inventors: |
Okada, Yasumasa; (Kyoto-shi,
JP) ; Kobayashi, Hitoshi; (Kyoto-shi, JP) ;
Nozato, Shoji; (Kyoto-shi, JP) ; Sawada,
Takahiko; (Kyoto-shi, JP) ; Hiratani, Kazuaki;
(Chuo-ku, JP) ; Otsuki, Toshihiro; (Chuo-ku,
JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
Sekisui Chemical Co., Ltd.
Osaka-shi
JP
|
Family ID: |
19062905 |
Appl. No.: |
10/207853 |
Filed: |
July 31, 2002 |
Current U.S.
Class: |
349/96 |
Current CPC
Class: |
G02B 5/3033 20130101;
G02B 1/111 20130101; C09K 2323/00 20200801; G02F 1/133528 20130101;
Y10T 428/31938 20150401; C09K 2323/031 20200801; G02B 1/14
20150115 |
Class at
Publication: |
349/96 |
International
Class: |
G02F 001/1335 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 31, 2001 |
JP |
2001-230749 |
Claims
What is claimed is:
1. A polarizer protection film obtained by melt film formation of a
norbornene resin having (1) a glass transition temperature Tg
(measured in accordance with JIS K 7121) of 135.degree. C. to
180.degree. C., and (2) an inherent viscosity (.eta..sub.inh) of
0.4 or more, which is calculated by the following equation (1) from
the drop time T (sec.) between marked lines measured at 30.degree.
C. with an Ubbelohde viscometer for a solution of the resin in
chloroform having a resin concentration of C (g/dl) and the drop
time B (sec.) between marked lines measured at 30.degree. C. with
an Ubbelohde viscometer for chloroform, the solvent, wherein (3)
the above-mentioned Tg and .eta..sub.inh are within the range
indicated by the following equation (2): .eta..sub.inh={ln(T/B)}/C
(1) T: the drop time (sec.) between marked lines of a sample
solution B: the drop time (sec.) between marked lines of a solvent
alone C: the concentration (g/dl) of the sample solution
45.eta..sub.inh.ltoreq.58.5-0.2Tg (2)
2. The polarizer protection film according to claim 1, wherein the
norbornene resin is obtained by copolymerizing monomers
indispensably containing at least one monomer A represented by the
following general formula (I) and at least one monomer B
represented by the following general formula (II): 2wherein R.sup.1
to R.sup.8 each independently represent an atom or a group selected
from the group consisting of hydrogen atom, a hydrocarbon group
having 1 to 10 carbon atoms and a polar group selected from the
group consisting of a halogen atom, an alkoxyl group, a hydroxyl
group, an ester group, a cyano group, an amido group, an imido
group and a silyl group, or a hydrocarbon group substituted by the
polar group; R.sup.1 to R.sup.8 may each independently represent a
group having an aromatic or heterocyclic ring; R.sup.1 or R.sup.2
and R.sup.3 or R.sup.4, or R.sup.5 or R.sup.6 and R.sup.7 and
R.sup.8 may combine with each other to form a monocyclic or
polycyclic structure; m is an integer of 1 to 3; and p is an
integer of 0 to 3.
3. The polarizer protection film according to claim 2, wherein
monomer A is
8-methyl-8-methoxycarbonyltetracyclo-[4.4.0.1.sup.2,5.1.sup.2,5.1.sup.-
7,10]-3-dodecene.
4. The polarizer protection film according to claim 2, wherein
monomer B is bicyclo[2.2.1]hept-2-ene.
5. A polarizing film for a liquid crystal display in which a
polarizer is laminated with the polarizer protection film according
to any one of claims 1 to 4 on at least one surfaces of the
polarizer.
6. A liquid crystal display in which the polarizing film for a
liquid crystal display according to claim 5 is laminated, with the
interposition of a pressure-sensitive adhesive.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a polarizer protection film
for protecting a polarizer having a polarization function of a
polarizing film used in a liquid crystal display.
BACKGROUND OF THE INVENTION
[0002] Liquid crystal displays which have recently been used for
many applications, such as personal computers and word processors,
exhibit a basic displaying performance by liquid crystal cells
having the function of changing a plane of polarization or a phase
of light by ON-OFF switching of an electric field and polarizing
films having an optical shutter function varying a transmission
state of light with a change in the plane of polarization or the
phase.
[0003] This polarizing film is a laminated product of a polarizer
having a polarization function and a protective film for securing
its durability or mechanical strength with the interposition of an
adhesive.
[0004] The polarization function of the polarizer is obtained by
orienting a light anisotropic absorber in a transparent polymer
film. There are, for example, a PVA-based polarizer obtained by
allowing iodine or a dichromatic dye to be adsorbed on polyvinyl
alcohol (hereinafter referred to as "PVA") film, followed by
uniaxial orientation by stretching, and a polyene-based polarizer
to which the polyene structure is given by dehydration or
dehydrochlorination of a stretched PVA or vinyl chloride film.
[0005] In the polarizer made of such a material, a problem of
deteriorated optical characteristics or dimensional shrinkage
caused by disorder of orientation in reliability test of such as
heat resistance is easily encountered, because PVA itself is a
hydrophilic polymer as for the PVA-based film, and because the
polarizer is wholly oriented by stretching, including the
polyene-based film. Accordingly, the polarizer made of the
above-mentioned material is provided with protective films on both
surfacesthereof. Theseprotectivefilmsarerequiredtohavehigh light
transmittance, no birefringence, excellent heat resistance,
moisture resistance, cold resistance and light resistance, and to
be optically uniform, that is to say, to have no foreign matter or
no streaky visual defects. Saponified solvent-cast films of
triacetyl cellulose (hereinafter referred to as "TAC") have
hitherto been used from the viewpoints of transparency, appearance
and easy adhesion to the polarizers.
[0006] However, the TAC film has a moisture permeability of about
300 g/m.sup.2/24 hours/100 .mu.m, so that the ability of it to
protect the polarizing film from the circumstances of high
temperature and humidity such as 60.degree. C. and 90% RH is
insufficient. Further, the TAC film has the problem that a phase
difference develops by a shrinkage stress of the polarizer in
reliability test of the polarizing film because of its high
photoelastic constant, which causes deterioration of a polarizing
performance.
[0007] As means for solving this problem, it has been proposed that
a norbornene resin sheet is used as a protective film for a
polarizer (refer to Japanese Patent Laid-open Publication (Hei)
06-51117). The norbornene resin is lower in the moisture
permeability and photoelastic constant than that of the TAC resin,
so that the norbornene resin is excellent in ability to protect the
polarizer under circumstances of high temperature and humidity or
in the reliability test.
[0008] The norbornene resin is largely restricted by a solvent when
a film thereof is formed by solvent casting. Accordingly, melt film
formation is preferred, considering economy. However, its molecular
skeleton contains many tertiary carbon atoms, so that it is easily
deteriorated by heat or oxygen.
[0009] Usually, as means for preventing deterioration of resins due
to heat or oxygen, various antioxidants such as a phenol
antioxidant and a phosphate antioxidant have been used. However, in
the case of the norbornene resin, it is very difficult to prevent
deterioration of the resin only by addition of an additive, because
of brittleness of the resin itself, and it is also difficult to
prevent dot-like defects such as fish eyes or appearance defects
such as die lines incident to local changes in melt viscosity.
SUMMARY OF THE INVENITON
[0010] An object of the present invention is to obtain a film
having optical uniformity and being sufficient to protect a
polarizer, by melt film formation of the above-mentioned norbornene
resin, thereby providing a highly reliable polarizing film and a
liquid crystal display using the same.
[0011] The present inventors have conducted intensive investigation
on the above-mentioned problems. As a result, the inventors have
discovered that the problems can be solved by using the following
film for protection of the polarizer. According to the invention,
there is provided a polarizer protection film obtained by melt film
formation of a norbornene resin having (1) a glass transition
temperature Tg (measured in accordance with JIS K 7121) of
135.degree. C. to 180.degree. C., and (2) an inherent viscosity
(.eta..sub.inh) of 0.4 or more, which is calculated by the
following equation (1) from the drop time T (sec.) between marked
lines measured at 30.degree. C. with an Ubbelohde viscometer for a
solution of the resin in chloroform having a resin concentration of
C (g/dl) and the drop time B (sec.) between marked lines measured
at 30.degree. C. with an Ubbelohde viscometer for chloroform, the
solvent, wherein (3) the above-mentioned Tg and .eta..sub.inh are
within the range indicated by the following equation (2):
.eta..sub.inh=v{ln(T/B)}/C (1)
[0012] T: the drop time (sec.) between marked lines of a sample
solution
[0013] B: the drop time (sec.) between marked lines of a solvent
alone
[0014] C: the concentration (g/dl) of the sample solution
45.eta..sub.inh.ltoreq.58.5-0.2Tg (2)
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0015] When the glass transition temperature (Tg) of the norbornene
resin used in the invention is lower than 135.degree. C., the
strength of the protective film is decreased under circumstances of
a temperature as high as 90.degree. C. or more under which the
polarizing film is used, and the function sufficient for protecting
the polarizer can not be exhibited. On the other hand, a norbornene
resin having a Tg exceeding 180.degree. C. brings about poor
appearance such as a reduction in surface smoothness caused by
gelation or non-uniform viscosity, because the molding temperature
exceeds the decomposition temperature of the resin itself. The
above-mentioned glass transition temperature is preferably from
140.degree. C. to 160.degree. C.
[0016] When the inherent viscosity (.eta..sub.inh) of the
norbornene resin used in the invention is less than 0.4, the
strength is insufficient for handling as a film, resulting in the
occurrence of the problem of breakage or cracks while the film runs
in a production line. The above-mentioned inherent viscosity is
preferably from 0.43 to 0.60.
[0017] Further, when Tg and .eta..sub.inh do not satisfy equation
(2), poor appearance such as a reduction in surface smoothness
caused by gelation or non-uniform viscosity is caused, similarly to
the case that Tg exceeds 180.degree. C.
[0018] The weight average molecular weight of the norbornene resin
used in the invention is usually 45,000 or more, and preferably
from 50,000 to 90,000.
[0019] The norbornene resins used in the invention include the
following copolymers:
[0020] (1) A ring-opening copolymer of monomer A represented by the
following general formula (I) and monomer B represented by the
following general formula (II) (each of monomer A and monomer B is
hereinafter also referred to as a "specific monomer");
[0021] (2) A ring-opening copolymer of monomer A represented by the
following general formula (I), monomer B represented by the
following general formula (II) and a copolymerizable monomer;
and
[0022] (3) A saturated copolymer obtained by addition
copolymerization of monomer A represented by the following general
formula (I), monomer B represented by the following general formula
(II) and an unsaturated a polymerizable double bond-containing
compound. 1
[0023] In general formulas (I) and (II), R.sup.1 to R.sup.8 each
independently represent an atom or a group selected from the group
consisting of hydrogen atom, a hydrocarbon group having 1 to 10
carbon atoms and a polar group selected from the group consisting
of a halogen atom, an alkoxyl group, a hydroxyl group, an ester
group (for example, an alkyl ester group), a cyano group, an amido
group, an imido group and a silyl group, or a hydrocarbon group
substituted by the above-mentioned polar group; R.sup.1 to R.sup.8
may each independently represent a group having an aromatic or
heterocyclic ring; R.sup.1 or R.sup.2 and R.sup.3 or R.sup.4, or
R.sup.5 or R.sup.6 and R.sup.7 and R.sup.8 may combine with each
other to form a monocyclic or polycyclic structure; m is an integer
of 1 to 3; and p is an integer of 0 to 3.
[0024] <Specific Monomers>
[0025] Of monomers A, preferred is a monomer represented by the
above-mentioned general formula (I) in which R.sup.1 and R.sup.3
are each hydrogen atom or a hydrocarbon group having 1 to 10 carbon
atoms, preferably 1 to 4, more preferably 1 or 2 carbon atoms,
R.sup.2 and R.sup.4 are each hydrogen atom or a monovalent organic
group, at least one of R.sup.2 and R.sup.4 is a polar group other
than a hydrogen atom or a hydrocarbon group, m is an integer of 1
to 3, p is an integer of 0 to 3, and m+p is preferably from 1 to 4,
more preferably 1 or 2, and particularly preferably 1.
[0026] The polar groups of the above-mentioned monomers A include a
halogen atom, a carboxyl group, a hydroxyl group, an ester group
such as an alkyl ester group or an aromatic ester group, an amino
group, an amido group, a cyano group, an ether group, an acyl
group, a silyl ether group and a thioether group. Of these, the
carboxyl group and the ester group are preferred, and the alkyl
ester group is particularly preferred.
[0027] Of monomers A, a monomer in which at least one polar group
of R.sup.2 and R.sup.4 is represented by a formula,
--(CH.sub.2).sub.nCOOR, is particularly preferred, because the
resulting norbornene resin has high glass transition temperature,
low moisture absorption and excellent adhesion to various
materials. In the formula representing the above-mentioned specific
polar group, R is a hydrocarbon group having 1 to 12 carbon atoms,
preferably 1 to 4 carbon atoms, more preferably 1 or 2 carbon
atoms, and preferably an alkyl group. Although n is usually from 0
to 5, lower n preferably causes in higher transition temperature of
the resulting norbornene resin. Further, a specific monomer in
which n is 0 is preferred in that its synthesis is easy and that
the norbornene resin having high glass transition temperature is
obtained.
[0028] Although monomers A can be used alone, two or more of them
may be copolymerized in order to obtain a copolymer having a glass
transition temperature specified in the invention.
[0029] Specific examples of the above-mentioned monomers A include
tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene,
pentacyclo[6.5.1.1.sup.3,6.0.sup.2,7.0.sup.9,13]-4-pentadecene,
8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene,
8-ethoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene,
8-n-propoxycarbonyl
tetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3dodecene,
8-iso-propoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene,
8-n-butoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene,
8-phenoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene,
8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodece-
ne,
8-methyl-8-ethoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dode-
cene,
8-methyl-8-n-propoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-
-dodecene,
8-methyl-8-iso-propoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.-
7,10]-3-dodecene,
8-methyl-8-n-butoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.-
sup.7,10-3-dodecene,
8-methyl-8-phenoxycarbonyltetracyclo[4.4.0.1.sup.2,5.-
1.sup.7,10]-3-dodecene,
8-ethylidenetetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]- -3-dodecene,
8-phenyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene and
8-methyl-8-phenyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]-3-dodecene.
[0030] Of these,
8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.su-
p.7,10]-3-dodecene is preferred as monomer A from the viewpoint of
a balance between heat resistance and water absorption of a
hydrogenated product of the resulting norbornene resin.
[0031] Specific examples of monomers B include but are not limited
to bicyclo[2.2.1]hept-2-ene, 5-methylbicyclo[2.2.1]hept-2-ene,
5-ethylbicyclo[2.2.1]hept-2-ene,
5-methoxycarbonylbicyclo[2.2.1]hept-2-en- e,
5-methyl-5-methoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-phenoxycarbonylbicyclo[2.2.1]hept-2-ene,
5-methyl-5-phenoxycarbonylbicy- clo[2.2.1]hept-2-ene,
5-cyanobicyclo[2.2.1]hept-2-ene,
5-ethylidenebicyclo[2.2.1]hept-2-ene,
8-ethylidenetetracyclo[4.4.0.1.sup.- 2,5.1.sup.7,10]-3-dodecene,
5-phenyl-bicyclo[2.2.1]hept-2-ene and
5-naphthylbicyclo[2.2.1]hept-2-ene (both types of .alpha. and
.beta. are available).
[0032] Of the above-mentioned specific examples of monomers B,
bicyclo[2.2.1]hept-2-ene is preferred from the viewpoint of
improved toughness of the resulting film.
[0033] <Copolymerizable Monomers>
[0034] Specific examples of the copolymerizable monomers include
cycloolefins such as cyclobutene, cyclopentene, cycloheptene,
cyclooctene and dicyclopentadiene. The carbon number of the
cycloolefin is preferably from 4 to 20, and more preferably from 5
to 12. They can be used either alone or as a combination of two or
more of them.
[0035] The range of monomer A and monomer B/the copolymerizable
monomer used is preferably from 100/0 to 50/50, and more preferably
from 100/0 to 60/40, by weight ratio.
[0036] <Ring-Opening Polymerization Catalysts>
[0037] The ring-opening polymerization reaction for obtaining (1) a
ring-opening copolymer of the specific monomers and (2) a
ring-opening copolymer of the specific monomers and the
copolymerizable monomer is conducted in the presence of a
metathesis catalyst.
[0038] This metathesis catalyst comprises (a) at least one selected
from compounds of W, Mo or Re in combination with (b) at least one
selected from compounds of the Ia group elements (for example, Li,
Na and K), the IIa group elements (for example, Mg and Ca), the IIb
group elements (for example, Zn, Cd and Hg), the IIIa group
elements (for example, B and Al), the IVa group elements (for
example, Si, Sn and Pb) or the IVb group elements (for example Ti
and Zr) in the periodic table of Deming, each compound having at
least one above-mentioned element-carbon bond or above-mentioned
element-hydrogen bond. In this case, in order to enhance activity
of the catalyst, (c) an additive described later may be added.
[0039] Typical examples of the compounds of W, Mo or Re suitable
for component (a) include compounds, such as WCl.sub.6, MoC.sub.6
and ReOCl.sub.3, described in Japanese Patent Laid-open Publication
(Hei) 1-132626, page 8, from upper left column, line 6 to upper
right column, line 17.
[0040] Specific examples of components (b) include compounds, such
as n-C.sub.4H.sub.9Li, (C.sub.2H.sub.5).sub.3Al,
(C.sub.2H.sub.5).sub.2AlCl, (C.sub.2H.sub.5).sub.1.5AlCl.sub.1.5,
(C.sub.2H.sub.5)AlCl.sub.2, methylalmoxane and LiH, described in
Japanese Patent Laid-open Publication (Hei) 1-132626, page 8, from
upper right column, line 18 to lower right column, line 3.
[0041] Although typical examples of components (c), the additives,
which can be suitably used, include alcohols, aldehydes, ketones
and amines, compounds described in Japanese Patent Laid-open
Publication (Hei) 1-132626, from lower right column, line 16 of
page 8 to upper left column, line 17 of page 9 can be further
used.
[0042] The metathesis catalyst is used in such an amount as to give
a molar ratio of the above-mentioned component (a) to the specific
monomers (component (a): specific monomers) of usually 1:500 to
1:100,000, and preferably 1:1,000 to 1:50,000.
[0043] The ratio of component (a) to component (b) ((a):(b)) is
from 1:1 to 1:50, and preferably from 1:2 to 1:30, by metal atom
ratio.
[0044] The ratio of component (a) to component (c) ((a):(c)) is
from 0.005:1 to 15:1, and preferably from 0.05:1 to 7:1, by molar
ratio.
[0045] <Solvents for Polymerization Reaction>
[0046] Solvents used in the ring-opening polymerization reaction
(solvents constituting molecular weight modifier solutions,
solvents for the specific monomers and/or metathesis catalysts)
include, for example, alkanes such as pentane, hexane, heptane,
octane, nonane and decane, cycloalkanes such as cyclohexane,
cycloheptane, cyclooctane, decalin and norbornane, aromatic
hydrocarbons such as benzene, toluene, xylene, ethylbenzene and
cumene, alkane halide or aryl halide compounds such as
chlorobutane, bromohexane, methylene chloride, dichloroethane,
hexamethylene dibromide, chlorobenzene, chloroform and
tetrachloroethylene, saturated carboxylic esters such as ethyl
acetate, n-butyl acetate, iso-butyl acetate and methyl propionate,
and ethers such as dibutyl ether, tetrahydrofuran and
dimethoxyethane. They can be used either alone or as a mixture of
them. Of these, the aromatic hydrocarbons are preferred.
[0047] The solvent is used in such an amount as to give "a solvent:
specific monomers ratio (weight ratio)" of usually 1:1 to 10:1,
preferably from 1:1 to 5:1.
[0048] <Molecular Weight Modifiers>
[0049] Although the molecular weight of the ring-opening copolymer
can be controlled by polymerization temperature, the kind of
catalyst and the kind of solvent, it is controlled by allowing a
molecular weight modifier to coexist in a reaction system.
[0050] Preferred examples of the molecular weight modifiers
include, for example, .alpha.-olefins such as ethylene, propene,
1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene and
1-decene. Of these, 1-butene and 1-hexene are particularly
preferred.
[0051] These molecular weight modifiers can be used either alone or
as a mixture of two or more of them.
[0052] The amount of the molecular weight modifier used is from
0.005 to 0.6 mole, and preferably from 0.02 to 0.5 mole, per mole
of specific monomer used in the ring-opening polymerization
reaction.
[0053] In order to obtain the ring-opening copolymer of (1) or (2),
the specific monomers and the copolymerizable monomer may be
polymerized by ring opening in a ring-opening polymerization stage.
However, the specific monomers may be polymerized by ring opening
in the presence of an unsaturated hydrocarbon polymer having two or
more carbon-carbon double bonds on its main chain such as
polybutadiene, polyisoprene, a styrene-butadiene copolymer, an
ethylene-non-conjugated diene copolymer or polynorbornene.
[0054] Although the ring-opening copolymer obtained as described
above can be used as such, a hydrogenated copolymer obtained by
hydrogenation is useful because of its excellent heat
stability.
[0055] <Catalysts for Hydrogenation>
[0056] The hydrogenation reaction is conducted by an ordinary
method, that is to say, by adding a catalyst for hydrogenation to a
solution of the ring-opening copolymer, and allowing hydrogen gas
of ordinary pressure to 300 atm., preferably 3 to 200 atm. to act
thereon at 0.degree. C. to 200.degree. C., preferably 20.degree. C.
to 180.degree. C.
[0057] As the hydrogenation catalyst, there can be used one
employed in the hydrogenation reaction of ordinary olefinic
compounds. The hydrogenation catalysts include heterogeneous
catalysts and homogeneous catalysts.
[0058] The heterogeneous catalysts include solid catalysts in which
noble metal catalytic materials such as palladium, platinum,
nickel, rhodium and ruthenium are carried on carriers such as
carbon, silica, alumina and titania. The catalysts may be either in
a powdery form or in a granular form.
[0059] The homogeneous catalysts include nickel
naphthenate/triethylalumin- um, nickel
acetylacetonato/triethylaluminum, cobalt octenoate/n-butyllithium,
titanocene dichloride/diethylaluminum monochloride, rhodium
acetate, chlorotris(triphenylphosphine)rhodium,
dichlorotris(triphenylphosphine)ruthenium,
chlorohydrocarbonyltris(triphe- nylphosphine)ruthenium and
dichlorocarbonyltris(triphenylphosphine)rutheni- um.
[0060] These hydrogenation catalysts are used in such an amount as
to give a ring-opening copolymer:hydrogenation catalyst ratio
(weight ratio) of 1:1.times.10.sup.-6 to 1:2.
[0061] As described above, the hydrogenated copolymers obtained by
hydrogenation have excellent heat stability, and their
characteristics are not deteriorated even by heating at the time
when they are molded, or when they are used as products. The
hydrogenation rate of double bonds of a main chain of the
ring-opening polymer is usually 50% or more, preferably 90% or
more, and more preferably 98% or more. The above-mentioned
hydrogenation rate can be measured at 60 MHz by .sup.1H-NMR.
[0062] Further, as the norbornene resin of the invention, there can
also be used (3) the saturated copolymer of the above-mentioned
specific monomers and the unsaturated polymerizable double
bond-containing compound.
[0063] <Unsaturated Polymerizable Double Bond-Containing
Compounds>
[0064] The unsaturated polymerizable double bond-containing
compounds include an olefinic compound having preferably 2 to 12
carbon atoms, more preferably 2 to 8 carbon atoms, such as
ethylene, propylene or butene.
[0065] The specific monomers/unsaturated polymerizable double
bond-containing compound ratio is preferably from 90/10 to 40/60,
and more preferably from 85/15 to 50/50, by weight ratio.
[0066] In the invention, ordinary addition polymerization can be
used for obtaining (3) the saturated copolymer of the specific
monomers and the unsaturated polymerizable double bond-containing
compound.
[0067] <Addition Polymerization Catalysts>
[0068] As a catalyst for synthesizing the above-mentioned saturated
copolymer (3), there can be used at least one compound selected
from a titanium compound, a zirconium compound and a vanadium
compound, and an organic aluminum compound as a promoter.
[0069] The titanium compounds used herein include titanium
tetrachloride and titanium trichloride, and the zirconium compounds
include bis(cyclopentadienyl)zirconium chloride and
bis(cyclopentadienyl)zirconiu- m dichioride.
[0070] As the vanadium compounds, there are used compounds
represented by the following general formula or electron-donor
thereof:
VO(OR).sub.aX.sub.b or V(OR).sub.cX.sub.d
[0071] Wherein R is a hydrocarbon group, X is a halogen atom,
0.ltoreq.a.ltoreq.3, 0.ltoreq.b.ltoreq.3, 2.ltoreq.(a+b).ltoreq.3,
0.ltoreq.c.ltoreq.4, 0.ltoreq.d.ltoreq.4 and
3.ltoreq.(c+d).ltoreq.4.
[0072] The above-mentioned electron donors include
oxygen-containing electron donors such as an alcohol, a phenol, a
ketone, an aldehyde, a carboxylic acid, an ester of an organic or
inorganic acid, an ether, an acid amide, an acid anhydride and an
alkoxysilane, and nitrogen-containing electron donors such as
ammonia, an amine, a nitrile and an isocyanate.
[0073] Further, as the organic aluminum compound used as a
promoter, there is used at least one selected from compounds each
having at least one aluminum-carbon bond or aluminum-hydrogen
bond.
[0074] In the above, for example, when the vanadium compound is
used, as for the ratio of the organic aluminum compound to the
vanadium compound, the ratio of aluminum atoms to vanadium atoms
(Al/V) is 2 or more, preferably from 2 to 50, and particularly
preferably from 3 to 20.
[0075] As solvents for the polymerization reaction used in addition
polymerization, the same solvents as used in the ring-opening
reaction can be used. The molecular weight of the resulting
saturated copolymer (3) is controlled usually by use of
hydrogen.
[0076] Thus obtained copolymer inevitably contains enormous amount
of carbon-carbon double bonds in its structure, so a hydrogenated
copolymer is preferable in respect of heat stability.
[0077] The amount of gels contained in the norbornene resin of the
invention is preferably as small as possible. When the amount of
gels is large, the occurrence of fish eye-like defects or die lines
is observed in a film obtained by melt film formation in some
cases. The amount of gels contained in a gram of the resin is
preferably 30 gels or less, more preferably 20 gels or less, and
particularly preferably 10 gels or less. Here, the amount of gels
contained in a gram of the resin is measured as described
below.
[0078] <Measurement of Gel Content>
[0079] Pellets accurately weighed are dissolved in THF to obtain a
THF solution having a concentration of around 5% by weight, and the
resulting solution is filtered by suction through a 0.5-.mu.m
membrane filter. The membrane filter after filtration is heated in
a muffle furnace at 260.degree. C. for about 30 minutes. Gels
(having a size of about 10 .mu.m or more, blurred in their contours
and observed brown) on the membrane filter are observed under a
stereoscopic microscope of 20 magnifications to count the number of
the gels.
[0080] There is no particular limitation on the polarizer which can
be used in the invention, as long as it has a function as a
polarizer. Examples thereof include the above-mentioned PVA-based
or polyene-based polarizer. There is no particular limitation also
on the method for producing the polarizer. For example, in the case
of the PVA-based polarizer, methods for producing the same include
a method of allowing iodine to be adsorbed on PVA film, followed by
uniaxial stretching of the film, a method of uniaxially stretching
a PVA film, followed by adsorption of iodine on the film, a method
of concurrently performing adsorption of iodine on a PVA film and
uniaxial stretching of the film, a method of dying a PVA film with
a dichromatic dye, followed by uniaxial stretching of the film, a
method of uniaxially stretching a PVA film, followed by dying of
the film with a dichromatic dye and a method of concurrently
performing dying a PVA film with a dichromatic dye and uniaxial
stretching of the film. In the case of the polyene-based polarizer,
methods for producing the same include known methods such as a
method of uniaxially stretching a PVA film, followed by heating and
dehydration in the presence of a dehydration catalyst, and a method
of uniaxially stretching a polyvinyl chloride film, followed by
heating and dehydration in the presence of a dehydrochlorination
catalyst.
[0081] In the invention, known antioxidants and ultraviolet
absorbers can be added in melt film formation, in order to prevent
deterioration of the film, and to improve reliability after
formation of polarizing plate. The antioxidants include, for
example, 2,6-di-t-butyl-4-methylphenol,
2,2'-dioxy-3,3'-di-t-butyl-5,5'-dimethyldiphenylmethane,
tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methan-
e, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene,
stearyl-.beta.-(3,5-di-t-butyl-4-hydroxyphenyl)propionate,
2,2'-dioxy-3,3'-di-t-butyl-5,5'-diethylphenylmethane, 3,9-bis
[1,1-dimethyl-2-{.beta.-(3-t-butyl-4-hydroxy-5-ethylphenyl)propionyloxy}e-
thyl]-2,4,8,10-tetraoxaspiro[5,5]undecane,
tris(2,4-di-t-butylphenyl)phosp- hite, cyclic
neopentanetetraylbis(2,6-di-t-butyl-4-methylphenyl]phosphite and
2,2-methylenebis(4,6-di-t-butylphenyl)octyl phosphite. The
ultraviolet absorbers include, for example,
2-(2'-hydroxy-5'-methylphenyl- )benzotriazole,
2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotri- azole,
2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole,
2-[2'-hydroxy-3'-(3",4",5",6"-tetrahydrophthalimidomethyl)-5'-methylpheny-
l]benzotriazole,
2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-[(2H-ben-
zotriazole-2-yl)phenol]),
2-(2H-benzotriazole-2-yl)-4,6-bis(1-methyl-1-phe- nylethyl)phenol,
2,4-dihydroxybenzophenone and 2,2'-dihydroxy-4,4'-methoxy-
-benzophenone. Further, in order to improve processability,
lubricants can also be added.
[0082] It is preferred that these additives have high weight
decreasing temperature and low vapor pressure. Low weight
decreasing temperature results in decomposition of the additives in
melt film formation to exert an adverse effect on surface
properties of the resulting film in some cases. Further, high vapor
pressure exerts an adverse effect on surface properties of the
resulting film, due to evaporation of the additives, in some cases.
Accordingly, of the additives used, at least the antioxidant and
the ultraviolet absorber have preferably a 5% weight decreasing
temperature of 300.degree. C. or more and a vapor pressure at
ordinary temperature and pressure of 1.times.10.sup.-9 Pa or less,
and more preferably a 5% weight decreasing temperature of
330.degree. C. or more and a vapor pressure at ordinary temperature
and pressure of 3.times.10.sup.-9 Pa or less.
[0083] Of these,
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl- )benzene
and tetrakis[methylene-3-(3,5-di-tbutyl-4-hydroxyphenyl)propionat-
e]methane are preferably used as the antioxidants, and
2,2'-methylenebis(4-(1,1,3,3-tetramethylbutyl)-6-[(2H-benzotriazole-2-yl)-
phenol]) and
2-(2H-benzotriazole-2-yl)-4,6-bis(l-methyl-1-phenylethyl)phen- ol
are preferably used as the ultraviolet absorbers.
[0084] These antioxidants and ultraviolet absorbers may be used
either alone or as a combination of two or more of them, and the
antioxidants may be used in combination with the ultraviolet
absorbers.
[0085] These antioxidants and ultraviolet absorbers are added
usually in an amount of 0.1 to 5 parts by weight, preferably in an
amount of 0.2 to 3 parts by weight, based on 100 parts by weight of
the norbornene resin. When the amount added is too small, no effect
of improving durability is obtained. On the other hand, when it is
too large, the appearance or optical characteristics of the
resulting film are deteriorated by bleedout to surfaces
thereof.
[0086] The thickness of the polarizer protection film of the
invention is usually from 10 to 100 .mu.m, and preferably from 20
to 80 .mu.m. When the thickness is too thin, tensile strength or
tear strength is insufficient, resulting in failure to obtain the
protective function of the polarizer. On the other hand, when it is
too thick, the problem arises that cost rises by reduced
processability in lamination or in cutting for forming the
polarizer protection film, or by a reduction in productivity.
[0087] In melt film formation for forming the polarizer protection
film of the invention, a single-screw extruder, a double-screw
extruder or a planetary multi-screw extruder is usually used. In
that case, in order to remove low molecular weight volatile
components such as water, gas, residual solvents, melt volatile
components and decomposed products, it is preferred that a drying
process is provided before the resin is supplied to the extruder,
or that the extruder is equipped with vent means. The resin melted
in the extruder can be extruded from a die for extruding the resin
into a melt sheet, such as a T-die or a hanger coat die, and
solidified by adhering the sheet to a cooling drum, thereby
obtaining the desired film. Adhering methods include a nip roll
system, an electrostatic application system, an air knife system, a
vacuum chamber system and a calender system. As for the cooling
drum for solidifying the melt sheet, a surface thereof made of
steel, nitriding steel or stainless steel is preferably
chrome-plated or treated with tungsten carbide for controlling its
releasability. It is desirable that the surface thereof has an Rmax
of 0.2 .mu.m or less for maintaining the smoothness of the
film.
[0088] The polarizer protection film of the invention is used as a
polarizing film for a liquid crystal display by laminating the
protection film with the above-mentioned polarizer on at least one
surface thereof.
[0089] As for laminating of a protection film on a polarizer, for
example, a protection film and a polarizer can be adhered by use of
a transparent adhesive or a pressure-sensitive adhesive. There is
no particular limitation on the laminating method, the kind of
agent and the kind of pressure-sensitive adhesive.
[0090] For example of the laminating method, there can be
mentioned, a laminating method (1) of adhering a protection film
and a polarizer directly with each other by an adhesive or a
pressure-sensitive adhesive and a laminating method (2) of
providing a primer layer on the surface of a protection film and
then adhering a polarizer thereon by an adhesive or a
pressure-sensitive adhesive. In method (2), the above primer layer
means under-coating layer provided in order to enhance the adhering
intensity between a protection film and an adhesive or a
pressure-sensitive adhesive. In order to provide a primer layer,
polyurethane or polyethyleneimine and the like can be under-coated
on a protection film.
[0091] In each above laminating method of (1) or (2), surface
treatment such as corona treatment of a protection film is
preferably conducted previously. It is preferable that after
surface treatment, the contact angle of distilled water on the
surface of a protection film is not more than 640, more preferably
not more than 600, particularly preferably not more than 550.
[0092] The above adhesive and pressure-sensitive adhesive include
both of organic solvent type and water type, and it can be employed
both of dry lamination process and wet lamination process.
[0093] As for adhesives, examples include PVA type adhesive,
urethane type adhesive, acrylic type adhesive, aqueous vinyl
urethane type adhesive and the like can be mentioned. Among them,
urethane type adhesive is preferred because of its high adhering
intensity and excellent durability.
[0094] As for pressure-sensitive adhesive used for laminating a
protection film on a polarizer, examples include a natural rubber
adhesive, a synthetic rubber adhesive, a vinyl acetate/vinyl
chloride copolymer adhesive, a polyvinyl ether adhesive, an acrylic
adhesive, a modified polyolefin adhesive and a silicone
adhesive.
[0095] As for coating method of an adhesive or a pressure-sensitive
adhesive on a polarizer, the coating solution is prepared at an
adequate concentration (such as 0.01 to 50% by weight) by diluting
an adhesive or a pressure-sensitive adhesive with water or organic
solvent, depending on the dry thickness, workability of coating and
the like. The above prepared solution can be coated and dried on a
polarizer by means of known devices such as gravure coater, micro
gravure coater.
[0096] The thickness of the dried adhesive layer or
pressure-sensitive adhesive layer is preferably from 0.001 to 30
.mu.m, and more preferably from 0.01 to 25 .mu.m.
[0097] Further, this polarizing film for a liquid crystal display
can be laminated, for example, in the order of a retardation film
and a liquid crystal cell (transparent electrode substrate), with
the interposition of a pressure-sensitive adhesive, thereby
constituting a liquid crystal display.
[0098] The pressure-sensitive adhesive is preferably one excellent
in transparency. Although there is no particular limitation
thereon, examples thereof include a natural rubber adhesive, a
synthetic rubber adhesive, a vinyl acetate/vinyl chloride copolymer
adhesive, a polyvinyl ether adhesive, an acrylic adhesive, a
modified polyolefin adhesive and a silicone adhesive. Of these, the
acrylic adhesive is preferably used in terms of heat resistance and
cost.
[0099] The thickness of the pressure-sensitive adhesive is
preferably from 5 to 100 .mu.m, and more preferably from 10 to 50
.mu.m. Less than 5 .mu.m results in easy separation of the film in
making a durability test, whereas exceeding 100 .mu.m results in
too high peel force, which causes a possibility of breakage of a
liquid crystal cell in carrying out a rework operation thereof.
[0100] According to the invention, the norbornene resin film having
very few appearance defects can be obtained by melt film formation
in which intact resin quality is maintained. The use of this film
can provide the polarizing film and the liquid crystal display
exhibiting the maximum performance of the norbornene resin and
having high reliability.
[0101] The invention will be illustrated with reference to examples
in more detail below, but the following examples are not intended
to limit the scope of the invention. Parts and percentages in the
examples and comparative examples are on a weight basis, unless
otherwise specified. Various measurements in the examples and
comparative examples were made as follows:
[0102] Inherent Viscosity (.eta..sub.inh)
[0103] Using chloroform as a solvent, the viscosity was measured at
a concentration of 0.5 g/dl at 30.degree. C. with an Ubbelohde
viscometer.
[0104] Glass Transition Temperature (Tg)
[0105] In accordance with JIS K 7121, the glass transition
temperature was measured at a rate of temperature increase of
10.degree. C./minute in an atmosphere of nitrogen with a
differential scanning calorimeter (DSC).
[0106] Evaluation Methods of Film
[0107] (1) Evaluation of Deterioration
[0108] For evaluating that deterioration did not occur during the
process of melt film formation of a film, the ratio of the
polystyrene-converted weight average molecular weight Mw.sub.1
after melt film formation to the weight average molecular weight
Mw.sub.0 of a intact material resin before melt film formation
(Mw.sub.1/Mw.sub.0) was used. the case that Mw.sub.1/Mw.sub.0 was
0.9 or more was indicated by .largecircle., and the case that it
was less than 0.9 was indicated by X.
[0109] The weight average molecular weight was measured in the
following manner, and the converted value according to standard
polystyrene was used.
[0110] Twenty milligrams of a sample was weighed into a flask, and
5 ml of tetrahydrofuran was added thereto, followed by standing for
24 hours. Then, a dissolved component was filtered through a
0.2-.mu.m filter, and gel permeation chromatography was carried out
under the following measuring conditions:
[0111] Apparatus: high performance liquid chromatograph
(manufactured by Hitachi, Ltd.)
[0112] Pump: L-6000
[0113] Detector: L-3300RI
[0114] Column: HSG60+HSG30+HSG20 (manufactured by SEKISUI FINE
CHEMICAL CO., LTD.)
[0115] Carrier: tetrahydrofuran (1.0 ml/minute)
[0116] Temperature: room temperature
[0117] Amount injected: 100 .mu.l
[0118] Calibration: a standard polystyrene sample, trade name
"Showdex" manufactured by SHOWA DENKO K.K.
[0119] (2) Appearance
[0120] A central portion of a film was visually observed. The case
that streaky poor appearance in an extrusion direction was observed
was evaluated as X, and the case that the poor appearance was not
observed was evaluated as .largecircle..
[0121] (3) Surface Roughness
[0122] In accordance with JIS B 0601, the center line average
height (Ra) and the maximum height (Rmax) were measured in a width
direction of a central portion of a film under the following
conditions:
[0123] Measuring equipment (Surface roughness tester): "Perthometer
C5D" (trade name) manufactured by MAHR GmbH (Germany)
[0124] Tracer: RFHTB 50 .mu.m
[0125] Analyzer: sas-2010
[0126] Analyzing conditions: measuring length: 3 mm, cutoff: 0.8
mm
[0127] (4) Performance of Polarizing Film
[0128] Preparation of Polarizer
[0129] A 75-.mu.m thick PVA film was immersed in water, and then,
uniaxially stretched 5 times in the machine direction. The
resulting film was immersed in an aqueous solution containing 0.5%
of iodine and 5% of potassium iodide while keeping the strained
state of the film to allow the dichromatic dye to be adsorbed.
Further, the film was subjected to crosslinking treatment while
keeping the strain in an aqueous solution containing 10% of boric
acid and 10% of potassium iodide at 50.degree. C. to obtain a
polarizer.
[0130] Preparation of Polarizing Film
[0131] Using an aqueous urethane adhesive, a polarizer was wet
laminated with norbornene resin films on both surfaces thereof
through a pair of rubber rolls, and dried at 50.degree. C. for 3
minutes, at 70.degree. C. for 3 minutes and at 80.degree. C. for 3
minutes. Then, the resulting product was cured at 45.degree. C. for
48 hours to obtain a polarizing film. As the adhesive, there was
used a composition in which 30 parts of a hardening agent and 520
parts of ion-exchanged water were compounded to 100 parts of the
aqueous urethane base resin (trade name: EL-436A/B, manufactured by
Toyo-Morton Ltd.). Corona treatment was applied to adhesive
surfaces of the norbornene resin films as pretreatment. The contact
angle of the corona-treated surface with distilled water was 430
(based on ASTM D5946-96).
[0132] Preparation of Acrylic Adhesive and Non-Support Tape
[0133] Toluene was added to a solution of an acrylic polymer in
ethyl acetate to dilute it, thereby preparing a 13% solution of the
acrylic polymer in toluene, the acrylic polymer being composed of
94.8 parts of butyl acrylate, 5 parts of acrylic acid and 0.2 part
of 2-hydroxyethyl methacrylate, and having a weight average
molecular weight (Mw) of 1,200,000 and a weight average molecular
weight (Mw)/number average molecular weight (Mn) ratio (Mw/Mn) of
3.9. A solution which was obtained by adding 2.0 parts of an
isocyanate crosslinking agent (Coronate L (manufactured by Nippon
Polyurethane Industry Co., Ltd.)) and stirring the resulting
mixture was applied onto a release film, and dried in two steps, at
60.degree. C. for 5 minutes and at 100.degree. C. for 5 minutes, so
as not to foam. Then, prepared was an easy release film able to be
released easier than the release film on which the above solution
is applied. The easy release film was laminated on the adhesive
surface in order to cover the adhesive temporarily, thereby
preparing a non-support tape having an adhesive thickness (average
value) after drying of 25 .mu.m.
[0134] Preparation of Test Piece for Evaluation and Durability
Test
[0135] Corona treatment was applied to one surface of the
norbornene resin film of the polarizing film thus prepared. The
non-support tape with an adhesive thickness of 25 .mu.m prepared
above, from which the easy release film was peeled off, was
laminated on the corona-treated surface to prepare a polarizing
film adhesive sheet.
[0136] The polarizing film adhesive sheet was punched with a
Thomson punching machine into a rectangular test piece having 12.1
in. between vertically opposite angles so that an absorption axis
of the polarizer made an angle of 45.degree. with a side. Further,
the release film left on the polarizing film adhesive sheet was
peeled off, and an adhesive surface thereof was adhered to a 1.2-mm
thick non-alkali glass plate with a bench laminator. Each of the
polarizing films was adhered to both surfaces of the glass plate so
that the absorption axes of two polarizers cross each other
orthogonally. After allowed to stand at room temperature for 1
hour, the glass plate was treated in an autoclave at 0.5 MPa for 20
minutes. After completion of the autoclave treatment, the glass
plate was allowed to stand at room temperature for 1 hour, and
subjected to the durability test (allowed to stand at 80.degree. C.
at a dry state for 250 hours, or at 60.degree. C. at 90% RH for 250
hours).
[0137] The optical durability characteristics before and after the
durability test were evaluated by changes in light transmittance.
The light transmittance was determined by measuring the parallel
light transmittance with a spectrophotometer (manufactured by
OTSUKA ELECTRONICS CO., LTD, RETS-2000) using a C light source by
CIE 1931 standard calorimetric system. The light transmittance of a
rectangular test piece was measured at 4 positions, in the middle
points of the four respective sides of the test piece and 10 mm
away from the side edges thereof, and the average value of
measurements at the four positions was determined.
REFERENCE EXAMPLE 1
[0138] 95 g of
8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.-
7/10]dodec-3-ene, 5 g of 5-ethyl-bicyclo[2.2.1]hept-2-ene, 60 g of
1,2-dimethoxyethane, 240 g of cyclohexane, 10 g of 1-hexene and 3.4
ml of a 0.96 mole/liter solution of diethylaluminum chloride in
toluene were introduced into an autoclave having an internal volume
of 1 liter.
[0139] On the other hand, 20 ml of a 0.05 mole/liter solution of
tungsten hexachloride in 1,2-dimethoxyethane and 10 ml of a 0.1
mole/liter solution of para-aldehyde in 1,2-dimethoxyethane were
mixed in another flask. This mixed solution (4.9 ml) was added to
the mixture in the above-mentioned autoclave. After sealing, the
mixture was heated at 80.degree. C., followed by stirring for 3
hours.
[0140] A 2/8 (weight ratio) mixed solvent of 1,2-dimethoxyethane
and cyclohexane was added to the resulting polymer solution to give
a polymer/solvent ratio of 1/10 (weight ratio), and then, 20 g of
triethanolamine was added thereto, followed by stirring for 10
minutes.
[0141] To this polymer solution, 500 g of methanol was added, and
the resulting solution was stirred for 30 minutes and allowed to
stand. An upper layer of two layers separated was removed, and
methanol was added again. After stirring and standing, an upper
layer was removed.
[0142] The same operation was further repeated twice, and the
resulting lower layer was appropriately diluted with
1,2-dimethoxyethane/cyclohexan- e mixed solvent to obtain a
1,2-dimethoxyethane/cyclohexane mixed solution having a polymer
concentration of 10%.
[0143] To this solution, 20 g of palladium/silica-magnesia
(manufactured by Nikki Chemical Co., Ltd., palladium content =5%)
was added, and the reaction was conducted in an autoclave at a
hydrogen pressure of 40 kg/cm.sup.2 at 165.degree. C. for 4 hours.
Then, the hydrogenation catalyst was removed by filtration to
obtain a hydrogenated copolymer solution.
[0144] Pentaerythritol-tetrakis[3-(3,5-di-t-butyl-4-hydroxy-phenyl)
propionate], an antioxidant, was added to this hydrogenated
copolymer solution in an amount of 0.1% based on the hydrogenated
copolymer, followed by desolvation at 380.degree. C. under reduced
pressure.
[0145] Then, the copolymer was melted and pelletized with an
extruder in an atmosphere of nitrogen to obtain thermoplastic resin
A. The glass transition temperature of this copolymer was
150.degree. C., .eta..sub.inh was 0.46, and the hydrogenation rate
was substantially 100%.
REFERENCE EXAMPLE 2
[0146] Polymerization, hydrogenation and palletizing were carried
out in the same manner as with Reference Example 1 with the
exception that 90 g of
8-methyl-8-methoxycarbonyltetracyclo[4.4.0.1.sup.2,5.1.sup.7,10]dodec--
3-ene, 10 g of bicyclo[2.2.1]hept-2-ene and 5 g of 1-hexene were
used, thereby obtaining thermoplastic resin B. The glass transition
temperature of this polymer was 140.degree. C., .eta..sub.inh was
0.62, and the hydrogenation rate was substantially 100%.
EXAMPLE 1
[0147] Thermoplastic resin A prepared in Reference Example 1 was
dried with a dryer equipped with a dehumidifier at a drying
temperature of 100.degree. C. for 4 hours, and then, extruded to a
film having a width of 455 mm and a thickness of 50 .mu.m,
according to the following melt film formation conditions:
[0148] Extruder: inner diameter: 50 mm, L/D: 28, extrusion
temperature: 230 to 300.degree. C.
[0149] Filter: leaf disk type filter, filtration precision: 3
.mu.m, filtration area: 0.8 m.sup.2
[0150] Extrusion die: width: 500 mm, coat hanger type
[0151] Extrusion amount: 20 kg/hour
[0152] Take-up unit: cooling roll temperature: 80.degree. C. to
145.degree. C., take-up speed: 14 m/minutes
[0153] Then, for the resulting film, (1) the evaluation of
deterioration, (2) the appearance and (3) the performance of the
polarizing film were evaluated as described above. Results thereof
are shown in Table 1.
EXAMPLE 2
[0154] An extruded film was obtained and evaluated in the same
manner as with Example 1 with the exception that resin B prepared
in Reference Example 2 was used, and the extrusion temperature was
changed to 270 to 320.degree. C., because of its different
extrusion suitability. Results thereof are shown in Table 1.
COMPARATIVE EXAMPLE 1
[0155] An extruded film was obtained and evaluated in the same
manner as with Example 1 with the exception that a commercially
available norbornene resin (trade name: "G6810", manufactured by
JSR Corporation, glass transition temperature: 172.degree. C.,
.eta..sub.inh:0.63) was used, and the extrusion temperature was
changed to 270 to 320.degree. C., because of its different
extrusion suitability.
[0156] The resulting film was poor in appearance, so that
evaluations as the polarizing film were not conducted. Results
thereof are shown in Table 1.
COMPARATIVE EXAMPLE 2
[0157] Using a commercially available 80-.mu.m TAC film (trade
name: "FUJITAC CLEAR", manufactured by FUJI PHOTO FILM CO., LTD.),
a polarizing film was prepared in the following manner.
[0158] A 5% aqueous solution of commercially available PVA (product
number: "PVA-117", manufactured by KURARAY CO., LTD.) was prepared.
This solution was applied onto the TAC film, and a polarizer was
wet laminated with the TAC film while stripping off excess aqueous
solution with a pair of rolls. The resulting film was dried with
hot air stepwise, at 50.degree. C. for 3 minutes, at 70.degree. C.
for 3 minutes and at 80.degree. C. for 3 minutes, to prepare a
polarizing film. Results thereof are shown in Table 1.
1 TABLE 1 Compara- Compara- tive tive Example 1 Example 2 Example 1
Example 2 Properties of Resin .eta..sub.inh 0.46 0.62 0.63 -- Tg
150 140 172 -- 45.eta..sub.inh 20.7 27.9 28.4 -- 58.5-0.2 Tg 28.5
30.5 24.1 -- Evaluation of Film Film Appearance .largecircle.
.largecircle. X -- Evaluation of Mw.sub.0 (.times. 10.sup.5) 7.2
9.0 10.2 -- Deterioration Mw.sub.1 (.times. 10.sup.5) 7.2 9.0 8.6
-- Evaluation .largecircle. .largecircle. X -- Surface Roughness Ra
(.mu.m) 0.038 0.041 0.128 -- Rmax (.mu.m) 0.294 0.31 1.07 --
Optical Durability Characteristics of Polarizing Film Changes in
Heat Resistance 0.02 0.02 -- 1.30 Transmit- (60.degree. C. dry
.times. tance (.DELTA. %) 250 hr.) Moisture 0.01 0.01 -- 1.07
Resistance (60.degree. C. 90% RH .times. 250 hr.)
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