Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
FILE, PtiT7N THiS AjW"N ~~
NO 94/18252 'Ff XfiTRANSLATION pCT/ZP94/00264
2155937
Description
Cycloolefin copolymers having high tear strength and low
optical attenuation
The invention relates to thermoplastic cycloolefin
copolymers (COCs) having high tear strength and low
optical attenuation, to a process for their preparation,
and to their use as optical waveguides (optical fibers).
Optical waveguides are employed for the transport of
light, for example for the purpose of illumination or
signal transmission. They generally comprise a cylindri-
cal, light-transmitting core surrounded by a cladding
layer of a likewise transparent material with a lower
refractive index. Thin-film optical waveguides comprise,
for example, three transparent layers, where the two
outer layers have lower refrfactive index than the
central layer. The conduction of light takes place by
total reflection at the inteface. Transparent materials
which can be employed are glasses or (organic or
inorganic) polymers.
The most widespread polymer for use as an optical wave-
guide, polymethyl methacrylate (PMIlKA), can only be
employed at up to about 85 C due to its low glass
transition temperature of about 106 C. Other known
transparent thermoplastics having higher glass transition
temperatures, such as, for example, polycarbonate or
aromatic polyesters, contain aromatic units in the
molecule. These result in increased light absorption in
the short-wave spectral region. The use of such polymers
for optical waveguides is described in illustrative terms
in A. Tanaka et al., SPIE, Vol. 840 (1987).
The heat distortion resistance can bje improved by
reaction of polymethacrylates. An exampXe which may be
mentioned is the polymer-analogous conversion of
_... ,._.. _..
2-155937 - z -
polymethyl methacrylate into polymethacrylimide. The
copolymerization of poly(meth)acrylate with comonomers
such as methacrylic anhydride or methacrylonitrile also
gives polymers of higher heat resisance than unmodified
PMMA. Another route to transparent polymers having
increased glass transition temperatures is the use of
(meth)acrylates of (per) halogenated or polycyclic ali-
phatic alcohols or of susbstituted phenols. The latter
likewise have increased light absorption in the short-
wave spectral region due to the aromatic units. Although
the former compounds give transparent polymers having
high glass transition temperatures, conversion, for
example, into optical fibers is difficult or impossible
due to their inherent brittleness.
All the classes of substances described are hygroscopic
due to their polar nature. At elevated temperature, the
water content in the polymer can cause undesired
degradation reactions during conversion, reducing the
practical use value.
However, lower water absorption is exhibited by thermo-
plastic COCs, which also have increased heat distortion
resistance. The complete absence of chromophores, such as
double bonds of all types, means that these polymers
appear particularly suitable for optical applications. It
should also be possible to employ these plastics in the
area of light conduction (EP-A 0 355 682 and
EP-A 0 485 893).
A particularly economical process is described in
European Patent Application EP-A 0 485 893, which
describes highly reactive metallocenes which polymerize
cycloolefins, in particular readily accessible
norbornene, to give copolymers having a high glass
transition temperature. However, experiments have shown
that these copolymers are relatively brittle. Although it
is known that the tear strength of a polymeric fiber can
be improved by orientation, processability is poor if the
2 94 7 8- 2 3 CA 02155937 2004-06-16
- 3 -
polymer becomes brittle immediately below the glass
transition temperature, as. is the case for the polymers
described in EP-A-0 485 893.
COCs can be prepared using specific Zieglercatalysts
(EP-A 0 355 682 and EP-A 0 485 893), usually using
alkylaluminum or alkylaluminum chlorides as cocatalysts.
However, these compounda hydrolyze during the work-up
process described to give extremely 'fine,. gelatinous
compounds which are difficult to filter. If alkylaluminum
chlorides are employed, chlorine- containingcompounds,
such. as hydrochloric acid or salts, which are likewise
difficult to separate off, are formed during work-up. If
hydrochloric acid ia employed for the work-up.
(EP-A 0 355 682 and EP-A 0 485 893), similar problems
arise. In particular in the processing of COCe.prepared
in this way, a brown coloration occurs. However, in
addition to a sufficiently high tear strength,'a further
important prerequisite for the use of a polyffier,for, the
production of a polymeric optical fiber or optical
waveguide is excellent transparency.
The=invention provides a process for the preparation of COCs
which are distinguished by improved tear strength, lower
optical attenuation, increased glass transition temperature
and low water absorption compared with the prior art.
Further, the invention provides an optical waveguide whose
core material comprises this COC.
It has now been found that copolym.erization of lower
alpha-olefins, cyclic olefias and/or polycycli;c olefins
using a catalyst system comprising at least one metal-
locene catalyst and at least one cocatalyst allows the
preparation of COCs having Ia high tear strength of
560-100 mPa, preferably 55-90 amPa, particularly prefer-
ably 58-85 mPa, if inetallocene catalysts of certain
syumetr.ies are employed. (The tear strength increases
with increasing molecular weight). If the reaction
215593 7 r 4 -
mixture formed after the copolymerization is subjected to
a specific work-up process, optical waveguides having a
low optical attenuation of 0.1-5 dB/m, preferably
0.2-2 dB/Im and particularly preferably 0.3-1.5 dB/m, can
be prepared from the purified COC and a transparent
polymer whose refractive index is lower than the
refractive index of the COC.
The invention thus relates to a process for the prepara-
tion of COCs having high tear strength by polymerization
of 0.1 to 99.9% by weight, based on the total amount of
the monomers, of at least one monomer of the formula I,
II, III or IV
CH\ R~
HC I CH~
11 R'-C-R" I
HC I CH
~CH~ Rs
CH ~CH2
H
CR3-C-R' CIH CH2 ( I I),
H C I CH-_'~
CH CHZ
CH CH R'
HC I C I CH
HIC R3-i-R' CI H RS-i -R' I (111),
__~C H~ C C H R i
/CH CH CH R
H ' CH/ CH/
R-C-R I Rs-C-R6 R'-C-Ra (iV),
HCCH---CHI
C c C H'~CH=~~R2
in which R1, R2, R3, R4, R5, R6, R7 and R8 are identical or
different and are a hydrogen atom or a C1-C8-alkyl
radical or a C6-C16-aryl radical, where identical radicals
in the various formulae can have different meanings,
2155937 -_ 5 _
from 0 to 99.9% by weight, based on the total amount of
the monomers, of a cycloolefin of the formula V
CH = CH
\ / (Y)
(CH2) n
in which n is a number from 2 to 10, and
from 0.1 to 99.9% by weight, based on the total amount of
the monomers, of at least one acyclic 1-olefin of the
formula VI
R9 . R10
C C (V i ~,
R11 ~ R12
in which R9, R10, R11 and R12 are identical or different
and are a hydrogen atom or a C1-C8-alkyl radical or a
C6-C16-aryl radical, in solution, in suspension, in a
liquid cycloolefin monomer, or cycloolefin monomer
mixture or in the gas phase, at a temperature of from -78
to 150 C, at a pressure of from 0.5 to 64 bar, in the
presence of a catalyst comprising a metallocene as
transition-metal component and an aluminoxane of the
formula VII
R13 R13 ~ /R13
AI - 0 - Al - 0- Al (VI I)
R13/ L ~n \R13
for the linear type and/or of the formula VIII
CA 02155937 2004-06-16
29478-23
- 6 -
F R' 3 1
I (Y111)
AI 0
L
n+Z
for the cyclic type, where, in the formulae VII and VIII,
R13 is a C1-C6-alkyl group or phenyl or benzyl, and n is
an integer from 2 to 50,, where the polymerization is
carried out in the presence of a catalyst whose
transition-metal component is at least one compound of
the formula IX
Rts
e
e
~ R1a
(tx)
R.~t Mt
(Rts)
Rt7
in which M1 is titanium, zirconium, hafnium, vanadium,
niobium or tantalum,
R14 and R15 are identical or different and are a hydro-
gen atom, a halogen atom, a C1-Clo-alkyl group, a
Cl-Clo-alkoxy group, a C6-C10-aryl group, a C6-Cio-
aryloxy group, a CZ-C10-alkenyl group, a C7 -C40-
arylalkyl group, a C7-C40-alkylaryl group or a
C8-C40-arylalkenyl group,
m may be one or two, depending on the valency of the
central atom M1,
Rl$ is
Re: Re= RIa Rig Rea R~e Rir R'e
I 1 1 i I
-112-- -ItY-Ya- . -Y=-CR= ='-- . - C-- - -11$- -C-C-
R10 = R:o :o :o R2e , R:o R:o Rte
=BR19, =A1R19, -Ge-, -Sn-, -0-, -S-, =SO, =SOZ, =NR190
=CO, = PR19 or =P (O) R19., where R~9, R20 and R21 are
identical or different and are a hydrogen atom, a halogen
215593 7-
7
atom, a C1-Clo-alkyl qroup, a C1-CIQ-fluoroalkyl qroup, a
C6-Clo-f].uoroaryl. group, a C6-Clo-aryl. group, a C1-C10-alkoxy
group, a C7-C10-al.kenyl group, a C7-C40-arylalkyl group, a CS-
C40-arylalkenyl group, or a C7-C40-alkylaryl group, or R19 and
20 19 21
R or R and R , in each case with t:he atoms connecting
them,form a ring,
M2 is silicon, germanium or tin,
R15 and R 17 are identical or different and are a monocyclic
or polycyclic hydrocarbon radical which can form a
sandwlc~1- structure with the central atom M wherein the
met:al.locene of the formula IX has Co-symmet ry w.ith
r "spect: to t:lle ligands R1 6 and R1 7 and with respect to
the cent ral. at:om M1 connect ing them in the case where R16
arid R17 are identical and has Cl-symmet ry in the case
where R16 arid R17 are different, and wherein, when the
copolymerizat:iorl is complete the copolymer is si.rbjected
to a work-up process which results i n opt ical attenuat ion
of the material of from 0.1 to 5dB/m.
Tn the polymerization, at least one polycyclic
olefin of the formula I, II, II, or IV, preferably a
cycl.oolefii-i "f the formula I or III
CH\. Ri
HC 1 4 CH
11 R -C-R
HC,j CH/R=
(I},
23221-5385
2155937
7a
H C CH--, C H CH
I
R'-C-R' CH2 (TT)
HC I CH
.~~''CH~ CH
CH CH R
H C I C H I CH
R}-C -R' I R C-R '
HCCHCHCHCH
2
(TTT
CH CH R
HCIHCH,-, CH~ ( CH
I' Ra_C_R' R -C-R R -C-R (TV
HCI /CHCHCHHCH~.'R2
C H C 23221-5385
-8- 2155937-
in which R1, R2, R3, R4, R5, R6, R7 and R8 are identical or
different and are a hydrogen atom or a Cl-CS-alkyl
radical or a Cl-C16-aryl radical, where identical radicals
in the various formulae can have different meanings,
is polymerized.
It is also possible to use a monocyclic olefin of the
formula V
CH - CH
\ / (V)
(CH2)n
in which n is a number from 2 to 10.
Another comonomer is an acyclic 1-olefin of the formula
VI
R9 R 10
\C C~/ (YI)
~
Ri> / R12
in which R9, R10, R11 and R12 are identical or different
and are a hydrogen atom or a C1-CB-alkyl radical, which
may also contain a double bond, or a C6-C16-aryl radical.
Preference is given to ethylene, propylene, butene,
hexene, octene or styrene. Particular preference is given
to ethene. In addition, it is also possible to employ
dienes.
in particular, copolymers of polycyclic olefins of the
formula I or II are prepared.
The polycyclic olefin (I to IV) is employed in an amount
of from 0.1 to 99.9% by weight, the monocyclic olefin (V)
is employed in an amount of from 0 to 99.9% by weight and
the acyclic 1-olefin (VI) is employed in an amount of
from 0.1 to 99.9%- by weight, in each case based on the
9- 2155937
total amount of the monomers.
The monomers are preferably incorporated in the following
ratios:
a) the molar polycyclic olef in (I to IV): 1-olef in (VI)
monomer ratio in the corresponding polymers is from
1:99 to 99:1, preferably from 20:80-to 80:20;
b) in polymers comprising polycyclic olefins (I to IV)
and monocyclic olefins (V), the molar polycyclic
olefin:monocyclic olefin ratio is from 10:90 to
90:10;
c) in polymers comprising polycyclic olefins (I to IV),
monocyclic olefins (V) and 1-olefins (VI), the molar
polycyclic olefin:monocyclic olefin:l-olefin monomer
ratio is from 93:5:2 to 5:93:2 to 5:5:90, i.e. the
molar ratio is within a mixture triangle whose
corners are determined by the molar ratios 97:1:2,
5:93:2 and 5:1:94;
d) in a), b) and c), polycyclic olefins, monocyclic
olefins and 1-olefins are also taken to mean
mixtures of two or more olefins of the particular
type.
The catalyst used in the polymerization comprises an
ali=inoxane and at least one metallocene of the formula IX
'6
R14
R'j / ',x'
!
~'~~RtS)n,
R' 7
in the formula IX, M1 is a metal from the group compris-
ing titanium, zirconium, hafnium, vanadium, niobium and
tantalum, preferably zirconium and hafnium.
CA 02155937 2004-06-16
29478-23
_ 10 -
R14 and R15 are identical or different and are a hydrogen
atom, a C1-C1a-s preferably Cl-C3-alkyl group, a Cl-Cio-,
preferably C1-C3-alkoxy group, a C6-C10, preferably C6-C8-
aryl group, a C6-Cl -, preferably C6-Ca-aryloxy group, a
C2-Cl0-, preferably C2-C4-alkenyl group, a C7-C4., prefer-
ably C7-CzO-arylalkyl group, a C'-C4Q-, preferably C7-C12-
alkylaryl group, a Ca-C4o-1 preferably C8-C1Z-arylalkenyl
group, or a halogen atom, preferably chlorine,
m can be one or two, depending on the valency of the
central atom Ml,
R16 and R17 are identical or different and are a mono-
cyclic or polycyclic hydrocarbon radical which can form
a sandwich structure with the central atom Ml.
The metallocene of the formula IX has Ca-sy=etry with
respect to the ligands R16 and R117 and with respect to the
central atom M1 connecting them in the case where R16 and
R17 are identical and has Cl-symmetry in the case where
R16 and R17 are di f f erent .
R16 and Rl7 are preferably indenyl and/or cyclopentadienyl
or alkyl- or aryl-substituted indenyl or cyclopenta-
dienyl,
R18 is a single- or multimembered bridge which links the
radicals R16 and R17 and is
Rig Ris R's Rrs Ras Rit R's Rts
I I i I I I
IA=- --Y=-MI, -4a._C8 _ =1- . ~-C- -O-M=- --C-C-~
R=o = Rio Rao , R:o ~$o , R:e Rao Rao
=BR19, =.A1R19, -Ge-, -Sn-, -0-, -S-, =SO, =SDa, =NR19,
=CO, = PRI9 or =P (0) R19, where R39, R20 and R21 are identi-
cal or different and are a hydrogen atom, a halogen atom,
preferably chlorine, a C1-C10- preferably C1-C3-alkyl
group, in particular a methyl group, a Cl-C10-fluoroalkyl
group, preferably a CF3 group, a C6-Cio-fluoroaryl group,
preferably a pentaf luorophenyl group, a C6-Cl , preferably
2155937
-11 -
C6-Cg-aryl group, a Cl-C10, preferably C1-C4-alkoxy group,
in particular a methoxy group, a Cz-Clp, preferably C2-C4-
alkenyl group, a C7-C401 preferably C7-Clo-arylalkyl
group, a C8-C40, preferably C8-C12-arylalkenyl group, or
a C7-C40, preferably C7-C12-alkylaryl group, or R19 and R20
or R19 and R21, in each case together with the atoms
connecting them, form a ring.
M2 is silicon, germanium or tin, preferably silicon or
germanium.
M1B is preferably =CR19R20, =SiR19R20, =Ger19R20, -0-, -S-,
=SO, =PR19 or =P (O) R19 .
The metallocenes can be prepared in accordance with the
following reaction scheme:
H2RII + ButyILl HRII LI
X
HzRI7 + ButylLi HR17L1
Ris - R17H + I-Butyi-LI --+
L i R 1 ~ - R i g - R1 7 LI + YIC14 !-+
R11
/ CI
Rit = ~I~
C 1 (IX)
or
N=R~~ + ButylL( HRIXL1
2155937_1Z
R R20
C HRLI RitR2oC
R,It b. H20 ~RIiH
2 9utrlti
1
R 17
RitR20C/ lT2
\Rit
~CI4
R1 4
R~t / i
, C 1
/C 1/
~ 'C I
R=0 R 17
ttli
R16 Rt6
t1 ~ Rtt ,
R /C1 R1SLi /CI
C -( t~ C i ---- 10/ C M t C I
R2o R 20 Qt7 Rt7
The above reaction scheme naturally also applies to the
case where R16 = R 17 and/or R19 = R20 and/or R14 = R15.
Preferred metallocenes are:
rac-dimethylsilylbis(1-indenyl)zirconium dichloride,
rac-dimethylgermylbis(1-indenyl)zirconium dichloride,
rac-phenylmethylsilylbis(1-indenyl)zirconium dichloride,
rac-phenylvinylsilylbis(1-indenyl)zirconium dichloride,
1-silacyclobutylbis(1'-indenyl)zirconium dichioride,
rac-ethylenebis(1-indenyl)zirconium dichloride,
rac-diphenylsilylbis(1-indenyl)hafnium dichloride,
rac-phenylmethylsilylbis(1-indenyl)hafnium dichloride,
rac-diphenylsilylbis(1-indenyl)hafnium dichloride,
rac-diphenylsilylbis(1-indenyl)zirconium dichioride,
- 13 - 2155937
isopropylene (cyclopentadienyl) (1-indenyl) zirconium
dichloride,
isopropylene((3-methyl)cyclopentadienyl)(1-indenyl)
zirconium dichloride,
dimethylsilyl(cyclopentadienyl)(1-indenyl)zirconium
dichloride, or mixtures thereof.
Dimethylsilylbis(2-methyl-l-indenyl)zirconium
dichloride.
Of these, particular preference is given to:
rac-dimethylsilylbis(1-indenyl)zirconium dichloride,
rac-phenylmethylsilylbis (1-indenyl) zirconium dichloride,
rac-phenylvinylsilylbis(1-indenyl)zirconium dichloride,
1-silacyclobutylbis(1'-indenyl)zirconium dichloride,
rac-ethylenebis(1-indenyl)zirconium dichloride,
rac-diphenylsilylbis(1-indenyl)zirconium dichloride,
isopropylene(cyclopentadienyl)(1-indenyl)zirconium
dichloride,
isopropylene((3-methyl)cyclopentadienyl)(1-indenyl)
zirconium dichloride,
dimethylsilyl(cyclopentadienyl)(1-indenyl)zirconium
dichloride, or mixtures thereof.
The cocatalyst is an aluminoxane of the formula VII
/R13
R~ R13 I
I
AI - 0 - Al - 0 - Al (YlI)
R13~ L Jn R13
for the linear type and/or of the formula VIII
~R13 1 ~ (viii)
AI - 0 -
L J n + 2
- 14 - 2155937
for the cyclic type. In these formulae, R13 is a Cl-C6-
alkyl group, preferably methyl, ethyl, isobutyl, butyl or
neopentyl, or phenyl or benzyl. Particular preference is
given to methyl. n is an integer from 2 to 50, preferably
to 40. However, the precise structure of the
aluminoxane is unknown.
The aluminoxane can be prepared in various ways.
in one of the processes, finely powdered copper sulfate
pentahydrate is slurried in toluene, and sufficient
trialkylaluminum is added in a glass flask under inert
gas at about -20 C so that about 1 mol of CuSO4=5H2O is
available per 4 Al atoms. After slow hydrolysis with
elimination of alkane, the reaction mixture is left at
room temperature for from 24 to 48 hours, during which
cooling may be necessary so that the temperature does not
exceed 30 C. The aluminoxane dissolved in toluene is
subsequently separated from the coppe2r sulfate by
filtration, and the solution is evaporated in vacuo. It
is assumed that this preparation process involves conden-
sation of low-molecular-weight aluminoxanes to give
higher oligomers with elimination of trialkylaluminum.
Aluminoxanes are furthermore obtained if trialkyl-
aluminum, preferably trimethylaluminum, dissolved in an
inert aliphatic or aromatic solvent, preferably heptane
or toluene, is reacted with aluminum salts, preferably
aluminum sulfate, containing water of crystallization, at
a temperature of from -20 to 100 C. In this reaction, the
volume ratio between solvent and the alkylaluminum used
is from 1:1 to 50:1, preferably 5:1, and the reaction
time, which can be monitored via elimination of the
alkane, is from 1 to 200 hours, preferably from 10 to 40
hours.
The aluminum salts containing water of crystallization
are in particular those which have a high content of
water of crystallization. Particular preference is given
to aluminum sulfate hydrate, in particular the compounds
Al2 (SO4) 3- 16H2O and Al2 (SO4) 3= 18HZ0 having the particularly
high water of crystallization contents of 16 and 18 mol
of H20/mol of A12(S04)3 respectively.
A further variant of the preparation of aluminoxanes
comprises dissolving trialkylaluminum, preferably tri-
methylaluminum, in the suspending medium, preferably in
the liquid monomer, in heptane or toluene, in the poly-
merization reactor and then reacting the aluminum com-
pound with water.
in addition to the processes outlined above for the
preparation of aluminoxanes, there are others which can
be used. Irrespective of the preparation method, all
aluminoxane solutions have in coamon a varying content of
unreacted trialkylaluminum, in free form or as an adduct.
This content has an effect on the catalytic activity
which has not yet been explained precisely and varies
depending on the metallocene compound employed.
it is possible to preactivate the metallocene by means of
an aluminoxane of the formula II and/or III before use in
the polymerization reaction. This significantly increases
the polymerization activity.
The preactivation of the transition-metal compound is
carried out in solution. It is preferred here to dissolve
the metallocene in a solution of the aluminoxane in an
inert hydrocarbon. Suitable inert hydrocarbons are
aliphatic or aromatic hydrocarbons. Preference is given
to toluene.
The concentration of the aluminoxane in the solution is
in the range from 1% by weight to the saturation limit,
preferably from 5 to 30% by weight, in each case based on
the entire solution. The metallocene can be employed in
the same concentration, but is preferably employed in an
amount of from 10-4 to 1 mol per mol of aluminoxane. The
29478-23 CA 02155937 2004-06-16
16 preactivation time is from 5 minutes to 60 hours, prefer-
ably from 5 to 60 minutes. The reaction temperature.is
from-78 C to 100 C, preferably from 0 to 70 C.
Significantly longer preactivation is possible, but
normally neither increases nor reduces the activity, but
may be appropriate for storage purposes.
The polymerization is carried out in an inert solvent
customary for the Ziegler low-pressure process, for
example in an aliphatic or cycloaliphatic hydrocarbon;
examples of these which may be mentioned are butane,
pentane, hexane, heptane, isooctane, cyclohexane and
methylcyclohexane. it is furthermore possible to use a
gasoline or hydrogenated diesel oil fraction which has
been carefully freed from oxygen, sulfur compounds and
moisture. It is also possible to use toluene, decalin and
xylene.
Finally, the monomer to be polymerized can also be
employed as solvent or suspending medium. in the case of
norbornene, bulk polymerizations of this type are carried
out at a temperature above 45 C. The molecular weight of
the polymer can be regulated in a known manner; hydrogen
is preferably used for this purpose.
The polymerization is carried out in a known manner in
solution, in suspension, in the liquid cycloolefin
monomer or cycloolefin monomer mixture or in the gas
phase, continuously or batchwise, in one or more steps,
at a temperature of from -78 to 150 C, preferably from
-20 to 80 C. The pressure is from 0.5 to 64 bar and is
established either by means of the gaseous olefins or
with the aid of inert gas.
Particularly advantageous are continuous and multistep
processes since they provide efficient use of the poly-
cyclic process the polycyclic olefin, which feed as
residual monomer together with the reaction mixture.
_ 17 - 2155937
The metallocene compound is used here in a concentration,
based on the transition metal, of from 10-3 to 10-7 mol,
preferably from 10-5 to 10-6 mol, of transition metal per
dm3 of reactor volume. The aluminoxane is used in a con-
centration of from 10-4 to 10-1 mol, preferably from 10-4
to 2= 10-2 mol, per dm3 of reactor volume, based on the
aluminum content. In principle, however, higher concent-
rations are also possible in order to employ the poly-
merization properties of various metallocenes.
In the preparation of copolymers, the molar ratios
between the polycyclic olefin and the 1-olefin employed
can be varied within a broad range. The choice of poly-
merization temperature, the concentration of the catalyst
components and the molar ratio employed allow the incor-
poration rate of comonomer to be controlled virtually as
desired. In the case of norbornene, an incorporation rate
of greater than 40 mol% is achieved.
The mean molecular weight of the copolymer formed can be
varied in a known manner by varying the catalyst concen-
tration or the temperature.
The polydispersity Mw/MA of the copolymers is extremely
narrow, with values between 1.9 and 3.5. This results in
a property profile of the polymers which makes them
particularly suitable for extrusion.
The copolymerization of polycyclic olefins with acyclic
olefins, in particular with propylene, gives polymers
having a viscosity index of greater than 20 cm3/g.
Copolymers of norbornene with acyclic olefins, in
particular ethylene, have a glass transition temperature
of above 100 C.
In order to prepare COCs having a low optical attenuation
of 0.1-5 dB/m, the reaction mixture is subjected to
purification. Purification is preferably carried out by
a process wherein, in a first step, the reaction mixture
2155937
- 18 -
is suspended with a filtration aid and with a substance
which precipitates the organometallic compounds in the
reaction mixture, the heterogeneous components are
filtered off in a second step, and, in a third step, the
purified COC is precipitated from the COC filtrate with
the aid of a precipitant or the solvent of the COC
filtrate is evaporated off.
In step 3, it is possible to employ evaporation methods
such as, for example, evaporation with the aid of a flash
chamber, a thin-film evaporator, a List compounder
(List, England), a vented extruder or a Diskpacks
(Farrel, IISA).
Substances which precipitate the organometallic compound
in the reaction mixture are preferably polar compounds,
such as water, ethylene glycol, glycerol and acetic acid.
The suspending medium is preferably a hydrocarbon.
Particularly suitable filtration aids are kieselguhr, for
example Celite 545 (LuV, Hamburg), Perlite, for example
OCelite Perlite J-100 (LuV), modified cellulose, for
example Diacel (LuV); porous carbon and absorptive
asbestos fibers are also suitable.
The use of filtration aids enables good filtration to be
achieved in the filtration step. Continuous or batch
filtration techniques can be employed. Filtration can be
carried out as a pressure filtration or a centrifugation.
The filtration is preferably carried out by means of
pressure filters, for example by filtration through a
nonwoven material, or by skimmer centrifugation. It is
also possible to use other conventional filtration
techniques. The filtered COC solution can be fed continu-
ously or batchwise a number of times through the same
filter so that the filtration action is further intensi-
fied. A suitable precipitant is acetone, isopropanol or
methanol.
in order to produce optical waveguides, the resultant
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polymers, which have been subjected to the above-described
purification step and have been dried, are melted using a
ram or screw extruder and forced through a die. A cladding
layer of a second polymer is applied to the resultant
filament, by coextrusion or by coating from a solution, the
refractive index of the second polymer being lower than that
of the core material. Suitable cladding materials are
polymers and copolymers of 4-methylpentene, inter alia
olefins, copolymers of ethylene and vinylidene fluoride,
with or without addition of other comonomers, such as, for
example, hexafluoropropene, tetrafluoroethylene, terpolymers
of tetrafluoroethylene, hexafluoropropene and vinylidene
fluoride, if desired also ethylene, copolymers of methyl
methacrylate and methacrylates of (partially) fluorinated
alcohols, for example tetrafluoro-n-propyl methacrylate.
In order to produce flat-film optical waveguides,
the polymers purified by the above-described process are
melted in an extruder and forced through a flat-film die.
The reflection layer on the surface can be applied by
coextrusion or by coating from solution with a second
polymer whose refractive index is lower than that of the
core material.
The cladding of the optical waveguide may comprise
a thermoplastic polymer having a refractive index of from
1.34 to 1.47 (at 589 nm).
The invention is described by the examples below.
Examples
Example 1
A clean and dry 75 dm3 polymerization reactor
fitted with stirrer was flushed with nitrogen and then with
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ethylene and charged with 22,000 g of norbornene melt (Nb)
and 6 liters of toluene. The reactor was then heated to a
temperature of 70 C with stirring, and 3.7 bar of ethylene
were injected. 500 cm3 of a toluene solution of
methylaluminoxane (10.1% by weight of methylaluminoxane
having a molecular weight of 1300 g/mol, according to
- 20 - 2155937
cryoscopic detezmination) were then metered into the
reactor, and the mixture was stirred at 70 C for 15
minutes, during which the ethylene pressure was kept
topped up at 3.7 bar. In parallel, 1200 mg of rac-
dimethylsilylbis(1-indenyl)zirconium dichloride were
dissolved in 500 cm3 of a toluene solution of methyl-
aluminoxane (concentration and quality see above) and
preactivated by standing for 15 minutes. The solution of
the complex (cat. solution) was then metered into the
reactor. For molecular weight regulation, 0.4 liter of
hydrogen was introduced at the outset. During the poly-
merization, 500 ml/h of hydrogen were metered in con-
tinuously. The mixture was then polymerized at 70 C for
2.5 hours with stirring (750 revolutions per minute),
during which the ethylene pressure was kept topped up at
3.7 bar.
The reaction solution was discharged into a 150 liter
stirred reactor containing 500 g of Celite 545 (LuV,
Hamburg) or alternatively cellulose filtration aid
( Diacel, LuV, Hamburg), 200 ml of water, 0.5 g of
peroxide decomposer ( Hostanox SE10, Hoechst) and 0.5 g
of antioxidant ( Hostanox 03, Hoechst) in 50 liters of a
hydrogenated diesel oil fraction ( Exsol, boiling range
100-120 C, Exxon). The mixture was stirred at 60 C for 30
minutes.
A filter cake of 500 g of Celite (or alternatively 500 g
of cellulose), suspended in 10 liters of Exsol, was
installed on the filter fabric of a 120 liter pressure
filter. The polymer solution was filtered through the
pressure filter in such a manner that the filtrate was
first returned to the filter for 15 minutes. A pressure
of up to 2.8 bar of nitrogen was built up above the
solution.
The filtrate was then filtered through seven filter
cartridges (Fluid Dynamics, Dynalloy XS64, 5 m,
0.1 m2/cartridge)=mounted in a steel housing. The polymer
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solution was stirred into 500 liters of acetone by means
of a disperser ( IIltraturax) and precipitated. During
this, the acetone suspension was circulated through a
680 liter stirred pressure filter with opened base valve.
The base valve was closed, and the product was washed
three times with acetone. 50 g of stabilizer
( Irganox 1010, Ciba) were added to the final wash. After
the final filtration, the product was predried at 100 C
in a stream of nitrogen and then dried for 24 hours at
0.2 bar in a drying cabinet. 5070 g of product were
obtained. A viscosity index (VI) of 61 cm3 (DIN 51562)
and a glass transition temperature (Tg) of 179 C were
measured on the product.
Example 2 (comparative example to Example 1)
A clean and dry 75 dm3 polymerization reactor fitted with
stirrer was flushed with nitrogen and then with ethylene
and"charged with 22,000 g of norbornene melt (Nb) and
6 liters of toluene. The reactor was then heated to a
temperature of 70 C with stirring, and 3.7 bar of
ethylene were injected. 500 cm3 of a toluene solution of
methylaluminumoxane (10.1% by weight of inethylaluminoxane
having a molecular weight of 1300 g/mol, according to
cryoscopic determination) were then metered into the
reactor, and the mixture was stirred at 70 C for 15
minutes, during which the ethylene pressure was kept
topped up at 3.7 bar. In parallel, 1200 mg of rac-
dimethylsilylbis(1-indenyl,)zirconium dichloride were
dissolved in 500 cm3 of a toluene solution of methyl-
aluminoxane (concentration and quality see above) and
preactivated by standing for 15 minutes. The solution of
the complex (cat. solution) was then metered into the
reactor. For molecular weight regulation, 0.4 liter of
hydrogen was introduced at the outset. During the poly-
merization, 500 ml/h of hydrogen were metered in con-
tinuously. The mixture was then polymerized at 70 C for
2.5 hours with stirring (750 revolutions per minute),
during which the ethylene pressure was kept topped up at
22 -
3.7 bar. 21559 37
The reactor contents were then quickly discharged into a
stirred vessel containing 200 cm3 of isopropanol (as
stopper). The mixture was precipitated in acetone and
stirred for 10 minutes, and the suspended polymer solid
was then filtered off. The filtered-off polymer was then
added with a mixture of two parts of 3 normal hydro-
chloric acid and one part of ethanol, and the mixture was
stirred for 2 hours. The polymer was then re-filtered,
washed with water until neutral and dried at 80 C and
0.2 bar for 15 hours. 4830 g of product were obtained. A
viscosity index VI of 63 cm3 (DIN 51562) and a glass
transition temperature (Tg) of 178 C were measured on the
product.
Example 3 (Comparative example to Example 1)
The'process was analogous to Example 1. However, the
catalyst used was 350 mg of diphenylcarbyl(cyclopenta-
dienyl)(9-fluorenyl)zirconium dichloride. After a reac-
tion time of 60 minutes, at an ethylene pressure of
3.4 bar and using the work-up process described in
Example 1, 4160 g of polymer were obtained, on which a VI
of 62 cm3 (DIN 51562) and a Tg of 181 C were measured.
- 23 - 211559 37
Table 1
COC (Example 1) COC (Example 3)
Tear strength/MPa 61 39
(DIN 53457)
Example 4
The polymer from Example 1 is melted in a ram extruder at
a barrel temperature of from 230 to 275 C and forced at
a flow rate of 610 cm3/h through a die having an internal
diameter of 2 mm. A terpolymer of tetrafluoroethylene,
vinylidene fluoride and hexafluoropropene having a melt
flow index of 32 g/10 min at 265 C and a load of 11 kg is
melted in a ram extruder and conveyed at a flow rate of
39 cm3/h to an annular slit arranged concentrically
around the core die. The core/cladding fiber produced is
cooled in a spinning bath and taken up at a rate of
5.5,m/min. In order to improve the mechanical properties,
the fiber is subsequently stretched at 190 C in a hot-air
oven at a ratio of 1:2.5 and then wound up. A core/
cladding fiber having a core diameter of 970 m and a
cladding diameter of 1 mm is obtained.
Tear strength 8 cN/tex
Elongation at break 35%
Optical attenuation 1.4 dB/m (650 mm)
Example 5
The polymer from Example 2 is melted in a ram extruder at
a barrel temperature of from 230 to 275 C and forced at
a flow rate of 610 cm3/h through a die having an internal
diameter of 2 mm. A terpolymer of tetrafluoroethylene,
vinylidene fluoride and hexafluoropropene having a melt
flow index of 32 g/10 min at 265 C and a load of 11 kg
is melted in a ram extruder and likewise conveyed at a
flow rate of 39 cm3/h to an annular slit arranged
concentrically around the core die. The core/cladding
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fiber produced is cooled in a spinning bath and taken
up at a rate of 5.5 m/min. In order to improve the
mechanical properties, the fiber is subsequently
stretched at 190 C in a hot-air oven at a ratio of 1:2.5
and then wound up. A core/cladding fiber having a core
diameter of 970 pm and a cladding diameter of 1 man is
obtained.
Tear strength 7.8 cN/tex
Elongation at break 40%
Optical attenuation 15.8 dB/m (650 mm)
