Note: Descriptions are shown in the official language in which they were submitted.
1303786
HOECHST AKTIENGESELLSCHAFT HOE 87/F 074 Dr.DA/je
Description
Transparent thermoplastic molding composition
The invention relates to a transparent, thermoplastic mol-
ding compos;tion which is suitable for the production of
polymeric glasses, articles for the optical industry and
optical fibers for transmission of light signals, and to a
process for the production thereof. The molding compo-
sition has a high thermal distortion resistance.
Optical fibers can comprise a core and a sheath, the corematerial always having a higher refractive index than the
sheath material. The core material and the sheath mate-
rial of such an optical fiber should absorb as littlelight as possible.
The polymeric materials employed the most frequently
hitherto for optical fibers are homopolymers and copoly-
mers of methyl methacrylate. Whereas halogen-containing
polymers have also been employed for the core, exclusively
- fluorine-containing polymers have hitherto been used for
the sheath since they have a lower refractive index. In
order to reduce light absorption, it has also already
been proposed to replace the hydrogen atoms in the mono-
mers and polymers by deuterium.
Copolymers of methyl methacrylate with a compound of the
formula CH2=CR-(CO-O)n-Ararm (R=H or CH3; n = zero
or 1, and m = 1 to 5) have been disclosed (cf. German
Offenlegungsschrift 2,202,791). Acrylates and methacry-
lates of mono-, di-, tri-, tetra- and pentabromophenol
have been mentioned by name.
Furthermore, a molding composition is known which com-
prises a polymeric ~-fluoroacrylate which can contain
deuteriu0 atoms both on the B-carbon atom of the vinyl
1;~03786
-- 2
group and in the alcohol component (European Application
Publication 0,128,517). These polymers are used as core
materials for optical fibers; they have a molecular
weight of 200,000 to 5,000,000 (gel permeation), a re-
fractive ;ndex of 1.45 to 1.60 and a softening point of
100 to 200C. The sheath material used for the optical
fibers are polymers which have a lower refractive index;
su;table for this purpose are, inter alia, polymers of ~-
fluoroacrylates whose alcohol component contains fluorine
atoms, for example trifluoroethyl ~-fluoroacrylate and
hexafluoroisobutyl ~-fluoroacrylate.
The preparation and properties of the abovementioned poly-
(fluoroalkyl ~-fluoroacrylates) are likewise known
(European Application Publication 0,128,516). The poly-
mers are obtained by free-radical ;nitiated bulk, solu-
tion or suspension polymerization of the monomers in the
presence of a chain-transfer agent at a temperature of 0
to 100C. The polymers have a molecular weight of
200,000 to 5,000,000 (gel permeation), a refractive index
of 1.36 to 1.44 and a softening point of 80 to 140C.
In add;tion, an opt;cal fiber has been described whose
- core material is produced by block polymerization of,
;nter al;a, halogenated aryl methacrylates, for example
pentafluorophenyl methacrylate (cf. Japanese Published
Specificat;on 60-242,404).
Furthermore, polyhalogenated aryl(fluoro/meth)acrylate-
conta;n;ng polymers have been proposed as materials for
polymer;c opt;cal f;bers. Finally, polymers have been
disclosed which were produced by polymerization of two
allyl alcohol groups which have been ester;fied using the
carboxylic acid groups of 1,4,5,6,7,7-hexachlorobicyclo-
hept-5-ene-2,3-d;carboxylic acid (cf. Japanese Published
Specification 61-51,901).
However, such polymers cannot be processed thermoplasti-
cally since they crosslink during the polymerization.
1303786
-- 3
Polymers which contain the 1,4,5,6,7,7-hexachloro[2.2.1]-
bicyclohept-5-en-2-yl group in the alcohol part of acry-
lates and methacrylates have also long been known (cf.
US Patent 3,022,277). ~owever, nothing has been disclosed
on the optical properties, the thermal distortion resis-
tance and the processing properties of these polymers, or
on the properties of copolymers with other acrylates and
methacrylates.
1û The object ~as to provide a polymer which can be prepared
in a simple and economical fashion and which can be pro-
cessed into objects of high transparency and thermal dis-
tortion resistance.
It has been found that a transparent thermoplastic mold-
ing composition which is essentially derived from an ester
of a (meth)acrylic acid with a bicyclic alcohol, it being
possibLe for the acid and alcohol radical to be deuterated
and/or halogenated, is capable of achieving the object.
The invention thus relates to a transparent thermoplastic
molding composition comprising 10 to 100% by weight of
units which are derived from an ester of the formula (I)
R6
C
R~ R3 1 (R5)~ ¦ \ ( I )
2,C = C - C - O - C ~C /
R
in wh;ch R6
R1 denotes a hydrogen, deuterium or fluorine atom,
R2 denotes a hydrogen, deuterium or fluorine atom,
R denotes a hydrogen, deuterium, fluorine, chlorine
or bromine atom, a cyano group, or a methyL group in
which all or some of the hydrogen atoms may be replaced
by deuterium, fluorine or chlorine atoms,
R4 denotes a hydrogen or deuterium atom or a C1- to
Cs-alkyl group in which all or some of the hydrogen
1303786
-- 4 --
atoms may be replaced by deuterium or fluorine atoms,
R5 denotes a -CHR9 or -CDR9 group in which R9 is a hydro-
gen, deuter;um, fluorine, chlorine or bromine atom or
a C1- to Cs-alkyl group in wh;~h all or some of the
S hydrogen atoms may be replaced by deuterium or fluor-
ine atoms,
R6 denotes a fluorine, chlorine or bromine atom or a tri-
fluoromethyl group,
R7 denotes a -CH2 group in which all or some of the hydro-
gen atoms may be replaced by deuterium, fluorine, chlor-
ine or bromine atoms, by two CH30 groups or by one 1',
2' -ethanediyldioxy group, denotes a carbonyl group or
an ethylene group ;n which all or some of the hydrogen
atoms may be replaced by deuterium, chlorine or bromine
atoms or by an oxo (0=) group,
R8 denotes a -CR10=CR10 group in ~hich R10 is a fLuor-
ine, chlorine or bromine atom or a trifluoromethyl
group, or denotes a -C(R11)2-C(R11)2 group in which
R11 is a fluorine atom or a trifluoromethyl group,
and
n is zero or 1, n not being zero when R7 is a -CH2- or
carbonyl group, and
90 to 0% by weight of units which are derived from other
- copolymerizable vinyl compounds.
In addition, the invention also relates to the process for
the production of these molding compositions and to the
transparent optical objects produced from the molding
composition.
In formula (I),
R1 is preferably a hydrogen, deuterium or fluorine atom,
in particular a hydrogen or deuterium atom,
R2 is preferably a hydrogen, deuterium or fluorine atom,
in particular a hydrogen or deuterium atom,
R3 ;s preferably a hydrogen, deuterium or fluorine atom,
or a methyl group in which all or sone of the hydrogen
atoms may be replaced by deuterium atoms, in particular
- 1303786
-- 5 --
is a deuterium or fluorine atom or a trideuteromethyl
group,
R4 is preferably a hydrogen or deuterium atom,
R5 is preferably a methylene, deuteromethylene or
chloromethylene group, in particular a methylene or
deuteromethylene group,
R6 is preferably a chlorine or bromine atom or a tri-
fluoromethyl group, in particular a chlorine or bromine
atom,
R7 is preferably a methylene group in ~hich the hydro-
gen atoms may be replaced by deuterium, chlorine or
bromine atoms or by t~o methoxy groups, is a carbonyl
group or an ethylene group in ~hich the hydrogen atoms
may be replaced by chlorine atoms or by an oxo group,
in particular is a -CH2-, -CD2-, -CCl2-, -C8r2-, -CHCl-,
-C(=0)-, -C(=0)-CCl2- or -CH2-CH2- group,
R8 is preferably a -CR10=CR10- group in which R10 may
denote a chlorine or bromine atom or a trifluoromethyl
group, in particular may denote a chlorine or bromine
atom, or is a -C(R11)2-C(R11)2- group in ~hich R11 may
denote a fluorine atom or a trifluoromethyl group,
and
n is preferably 1.
The acid component of the esters used according to the
invention is thus preferably acrylic acid, methacrylic
acid, rl-fluoroacrylic acid, ~,B-difluoroacrYlic acid or
the corresponding fully or partly deuterated compounds,
in particular perdeuteromethacrylic acid, perdeuteroacry-
lic acid, ~-fluoroacrylic acid or perdeutero-~-fluoro-
acrylic acid; the alcohol component is preferably
1,3,4,5,6,7,7-heptachlorobicycloC2.2.1]hept-5-en-2-ol,
1,4,5,6,7,7-hexachloro- or -hexabromobicycloC2.2.1]hept-
5-en-2-ol, 1,4,5,6,7-pentachlorobicycloC2.2.1]hept-5-
35 en-2-ol, 1,4,5,6-tetrachlorobicycloC2.2.1]hept-5-en-2-ol,
1,2,3,4-tetrachlorob;cycloC2.2.13hept-2-en-7-ol, 1,4,5,6-
tetrakis(trifluoromethyl)-7-oxo- or -7-bis(methoxy)-
bicycloC2.2.1]hept-5-en-2-ol, 1,2,3,4-tetrakis(tri-
fluoromethyl)bicycloC2.2.1]hept-2-en-7-ol, 1,2,3,4-
~03786
-- 6
tetrabromo-5,6-dichlorobicyclot2.2.1]hept-2-en-7-ol,
1,2,3,4-tetrachloro-5,6-dibromobicyclo~2.2.1]hept-2-en-
7-ol, 5,5,6,6-tetrakis(trifluoromethyl)bicycloC2.2.1]
heptan-2-ol, 5,5,6,6-tetrafluorobicyclo[2.2.1~heptan-
2-ol, 1,4,5,5(or 6,6),7,8-hexachloro-6(or 5)-oxobicyclo
C2~2.1]oct-7-en-2-ol or 1,4,5,5,6,6,7,8-octachloro-
bicyclot2.2.1]oct-7-en-2-ol, in particular 1,4,5,6,7,7-
hexachloro- or -hexabromobicyclot2.2.1]hept-5-en-2-ol,
1,4,5,6,7-pentachlorobicyclot2.2.1]hept-5-en-2-ol,
1,4,5,6-tetrachlorobicyclot2.2.1]hept-5-en-2-ol,
5,5,6,6-tetrak;s(trifluoromethyl)bicyclot2.2.1]heptan-
2-ol, 5,5,6,6-tetrafluorobicyclot2.2.1]heptan-2-ol,
1,4,5,5(or 6,6),7,8-hexachloro-6(or 5)-oxobicyclo-
t2.2.1]oct-7-en-2-ol.
According to the invention, those esters are preferabLy
used in whose alcohol and ac;d component the hydrogen
atoms have been substituted as fully as possible by
deuterium, fluor;ne, chlorine and bromine atoms or by
trifluoromethyl groups, in particular esters of perdeu_
teromethacrylic acid, perdeuteroacrylic acid, ~-fluoro-
acrylic acid or perdeutero-~-fluoroacrylic acid with
1,4,5,6,7,7-hexachloro- or -hexabromobicyclo[2.201]
- hept-5-en-2-ol-2,2,3-d3,1,4,5,6,7-pentachlorobicyclo
t2.2.1~hept-5-en-2-oL-2,2,3-d3, 1,4,5,6-tetrachloro-
bicyclot2.2.1~hept-S-en-2-ol-2,2,3-d3, 5,5,6,6-
tetrakis(trifluoromethyl)b;cyclot2.2.1~heptan-2-ol-
1,2,3,4,7,7-d6, 5,5,6,6-tetrafluoro-bicyclot2.2.1]
heptan-2-ol-1,2,3,4,7,7-d6 or 1,4,5,5(or 6,6),7,8-
hexachloro-6(or 5)-oxob;cyclot2.2.1]oct-7-en-2-ol-
2,2,3-d3.
The molding composition according to the invention com-
prises from 10 to 100, preferably 40 to 1ûO, in particu-
lar S0 to 80, ~ by weight of units which are derived from
an ester of the formula (I), and 90 to 0, preferably 60
to 0, in particular 50 to 20, % by weight of units ~hich
are derived from other copolymeri~able vinyl compounds.
Su;table compounds are C1- to C6-alkyl esters of acryl;c
i303786
-- 7 --
acîd, C1- to C6-alkyl esters of methacrylic acid, C1- to
C6-alkyl esters of ~-fluoroacrylic acid, styrene or sub-
stituted styrene. The esters of acrylic acid, methacrylic
ac;d and a-fluoroacrylic acid, and the deuterated deriva-
tives thereof, are preferably used. In particular, methyl
acrylate, methyl methacrylate and methyl ~-fluoroacrylate
are employed, the corresponding deuterated compounds being
particularly preferred.
The molding composition according to the invention is
produced by free-radical block polymerization or suspen-
sion, emulsion or solution polymerization, in particular
by block polymerization, of a compound of the formula
~I) and, if appropriate, another copolymerizable vinyl
compound.
Suitable free-radicaL active initiators are azo compounds,
such as azo-bisisobutyronitrile, azo-bis(cyclohexylcarbo-
nitrile), azo-bis(tert.-octane) and 2-phenylazo-2,4-
dimethyl-4-methoxyvaleronitrile, and organ;c peroxides,
such as tert.-butyl peroxide, tert.-butyl peroctoate,
tert.-butyl peroxyisopropylcarbonate, tert.-butyl hydro-
peroxide and tert.-butyl peroxyisobutyrate. The amount
of initiator is in the range 0.001 to 3, preferably 0.035
to 0.3, mole per 100 moles of the monomer or monomers.
Polymerization is advantageously carried out in the pre-
sence of a chain-transfer agent (regulator). Suitable
for this purpose are, in part;cular, mercaptans, such as
butyl mercaptan, tert.-butyl mercaptan, propyl mercaptan,
phenyl mercaptan, tert.-hexyl mercaptan and butylene-1,4-
dithiol, and esters of mercaptoacetic acid, for example
ethyl mercaptoacetate and ethylene glycol bis(mercapto-
acetate). The polymerization temperature is 60 to 180C,
preferably 80 to 160C, particularly preferabLy 100 to
160C.
It is advisable to degas the reaction mixture before
commencing the poLymerization For this purpose, the
reaction mixture comprising monomers, initiator and, if
1~03786
-- 8 --
appropriate regulator is initially cooled in a reactor
to a temperature of at least -80C the reactor is then
evacuated and ;n a sealed state warmed to a temperature
of 0 to 25C; this procedure can be repeated several
S times.
The molding composition according to the invention is
produced in the form of a glass-clear thermoformable
material. It is therefore sùitable above all as a
material for the production of transparent objects for
example resist materials lenses optical fibers and
alone or mixed with another polymer which has a different
refractive index as a material for optical data-storage
media. The spectral transparency of the molding compo-
sition is particularly h;gh in the wavelength range from
600 to 1 300 nm. The molding composition exhibits the
characteristic properties belo~:
Mean molecular weight 8 000 to 5 00û 000 preferably
50 C00 to 200 000 (measured by the light-scattering
method).
Glass-transition temperature 95 to 250C preferably 120
- to 200C particularly preferably 150 to 180C.
Decomposition temperature at least 230C preferably 250
to 300C.
The objects manufactured from the molding composition
according to the invent;on have an excellent thermal dis-
tortion res;stance and are nonflammable.
The follo~ing Examples serve to illustrate the invention
in greater detail. Percentages in each case relate to
the weight.
1~03786
_ 9 _
Exa-ple 1
1~ 1,2,3,4,7,7-Hexachlorob;cyclo[2.2.1]hept-2-en-5-yl
acetate
s
100 9 (0.366 mol) of hexachlorocyclopentadiene and
37 g (0.43 mol) of vinyl acetate were refluxed in a
250 ml three-neck flask equipped with magnetic
st;rrer, thermometer and reflux condenser. During re-
fluxing, the temperature cf the reaction mixture was
initially 87C and towards the end, after 40 hours,
139C. The mixture was subjected to fractional dis-
tillation, ~5 9 of the ester being obtained as the
main fraction at 105-112C (0.05 mbar) (72% of theory).
2) 1,2,3,4,7,7-Hexachlorobicyclot2.2.1]hept-2-en-5-ol
1,760 ml of methanol and 17.6 ml of concentrated
hydrochloric acid were added to 880 9 (2.45 mol) of
compound 1 in a 4 l three-neck flask equipped with
magnetic stirrer, thermometer and reflux condenser,
and the mixture was refluxed for 4 hours. The solvent
was then evaporated and the solid residue was recrys-
- tallized from n-heptane, 704 g of the alcohol being
obtained (~0% of theory).
3) 1,2,3,4,7,7-Hexachlorobicyclo[2.2.1]hept-2-en-5-yl
acrylate (AHC)
50 9 (0.158 mol) of compound 2 were dissolved in
150 ml of toluene in a 500 ml three-neck flask equipped
with magnetic stirrer, thermometer and reflux condenser,
and 21.5 9 (0.237 mol) of acryl chloride were added
at 70C. The mixture was subsequently stirred at
this temperature for a further 16 hours. The solvent
was then evaporated and the res;due distilled. The
fraction at around 118C ~60.6 9) was dissolved in
diethyl ether and filtered through an Al203 column.
After evaporation of the diethyl ether from the
~103786
- 10 -
filtrate, 33.4 9 of the acrylate were obtained t57%
of theory).
4) 1,2,3,4,7,7-Hexachlorobicyclo[2.2.1]hept-2-en-S-yl
methacrylate
(MA-HC)
200 9 (0.63 mol) of compound 2 were dissolved in
S00 ml of toluene in a 1 L three-neck flask equipped
with magnet;c stirrer, thermometer and reflux con-
denser, and 99.2 9 (0.95 mol) of methacryl chloride
were added. This mixture was then stirred under re-
flux for 30 hours. The solvent was subsequently
evaporated and the residue, dissolved in diethyl
ether, filtered through an Al203 column. After evapora-
tion of the diethyl ether, 189.4 9 of the methacrylate
were obtained (78% of theory).
ExaopLe 2
A solution of 100 parts of hexachlorobicycloheptenyl
acrylate (AHC), 0.05 part of dicumyl peroxide and 0.17
part of butyl mercaptan were filtered through a membrane
~ f;lter (pore s;ze 200 nm) into a glass vessel and care-
fully degassed. For this purpose, the reaction mixture
~as firstly frozen using liquid nitrogen, and the glass
vessel was then evacuated (0.001 mbar) and subsequently
warmed to room temperature. This procedure was repeated
three times. The reaction vessel was then sealed, and
the degassed reaction mixture was initially warmed for
30 5 hours at a temperature of 123C, then at a temperature
of 140C. After cooling to room temperature, a glass-
clear polymeric material was obtained on which the follow-
ing properties were measured.
35 Mean degree of polymerization Pw 2,050
Glass transition temperature159C
Decomposition temperature 270C
Melt flow index (250C; 3.8 kg)8 9/10 min
1303~86
Residual monomer content 0.5%
Refractive index n23 1.54
ExampLe 3
A solution of 50 parts of hexachLorobicycloheptenyl meth-
acrylate ~MAHC), 0.03 part of a~oisobutyronitrile and 0.5
part of butyl mercaptan in 50 parts of chloroform were
filtered and degassed analogously to Example 20 The de-
gassed reaction mixture was then warmed at a temperatureof 60C for 20 hours. After the batch had been cooled to
room temperature, 400 parts of acetone were added, and the
resultant mixture was transferred ;nto 6,000 parts of hex-
ane. The polymer which precipitates during this opera-
tion was separated from the liquid, reprecipitated fromacetone/hexane and dried for 6 hours at a temperature of
100C in vacuo. 40 9 (80Z of theory) of a polymer were
obtained on which the following properties were measured:
Mean degree of polymerization Pw 500
Glass transition temperature 220C
Decomposition temperature 300C
Exa~p~es 4 to 6
Solutions compr;sing various amounts of MAHC and methyl
methacrylate (MMA) and containing 0.1 9 of a20isobutyro-
nitrile and 0.15 g of butyl mercaptan in each case were
filtered and degassed analogously to Example 2. The de-
gassed reaction mixtures were each warmed to a tempera-
ture of 60C for 30 minutes and, after cooling to room
temperature, mixed with 300 ml of acetone. The mixtures
obtained in each case were transferred into 5 l of hexane,
and the precipitated copolymers were separated from the
liquid and dried for 6 hours at a temperature of 70C.
The respective composition of the monomer mixture and the
1303786
- 12 -
copolymer and the glass transition temperature (Tg) of
the copolymer can be seen from Table 1.
Table 1
Example MMA:MAHC weight ratio Tg (C) l nD23
Monomer Copolymer
mixture
.
4 28:72 23:77 161 1.529
51:49 40:60 155 1.523
6 70:30 59:41 147 1.513
~xaople 7
A mixture of 50 parts of MAHC and 50 parts of MMA, 0.05
part of tert.-butyl isopropylperoxycarbonate and 0.5 part
of butanedithiol was saturated with nitrogen in a (press-
ure-tight) reaction vessel equipped with stirrer and met-
ering device. The reaction solution was warmed ~o 90Cwhile stirring.
It was possible to detect a slight increase in v;scosity,
- and thus commencement of the reaction, from an increase
in the power consumption of the stirrer. A sample was
removed from the mixture 15 minutes after commencement
of polymerization, and the MMA:MAHC concentration ratio
was determined by gas chromatography. Corresponding to
the increased consumption of MAHC, further parts of a
mixture comprising 40 parts of MMA, 60 parts of MAHC,
0.05 par~ of butanedithiol and 0.4 part of tert.-butyl
isopropylperoxycarbonate were metered in continuously,
and the metering rate adjusted, in accordance with the re-
sults of further (gas chromatographic) analyses so that
a MMA:MAHC free monomer concentration ratio of 52:48 (9/9)
was maintained in the reaction vessel.
~hen the subsequent metering ~as complete, the reaction
mixture ~as heated to 160C over the course of 2 hours
1~03786
- 13
and kept at this temperature for 2 hours. The mixture
was subsequently transferred into a two-stage degassing
extruder where residual monomer was removed.
The glass transition point of the granulated material
was Tg = 157C, and the mean degree of polymerization
was Pw = 2,340.
Example 8
It was possible to mold the material from Example 2 in a
mold at 250C under pressure to form lenses and similar
optical objects. After the surface of a lens had been
polished, a transmission of 91% of the incident light was
achieved.
Transmission and image-formation properties of this lens
remained unchanged even after storage for 24 hours at
100C and an atmospheric humidity of 100 0bar.
Comparison ExampLe A
A lens molded under the conditions of Example 8 from a
polymeric glass element made from polymethyl methacrylate
- (PMMA) exhib;ted, after polishing, a transmission of 89X
and comparable image-formation properties. After storage
for only 2 hours at 120C, the surface of the lens was
clearly cloudy and the shape of the lens had changed so
substantially that a usable image was no longer produced.
Exa-ple 9
The polymerization by the method of Example 7 was repeated,
and the polymer was processed directly, without granula-
tion, to form an optical fiber. Of the light intensity
which was shone into the front face of the optical fiber,
it was possible to measure 45X after a length of three
meters, and 7G% after a length of one meter.
After the fiber had been stored for 7 days at 120C and
130~786
- 14 -
an atmospheric humidity of 100 mbar, it was st;ll possible
to detect 70% of the incident light intensity after a
Length of one meter and 43% after three meters.
S Comparison Example ~:
A three-meter length of an optical fiber made from PMMA
exhibited a transmission of 70% at the beginning of the
experiment. After storage at 110C for three hours, the
length of the fiber had already shrunk by half and the
transmission had dropped to 10% of the incident light
intensity.
