Note: Descriptions are shown in the official language in which they were submitted.
ZOG
This invention relates to an improved process for the
high-yield preparation of copolymers starting from ethylene
either alone or in mixture with one or more alpha-olefines,
and a compound containing two or more unsaturated olefine
~onds, which can be conjugated, the process comprising the use
of a catalytic system consisting of i) an organometalllc
compound of group III of the periodic system, and ii) a compound
prepared by reacting magnesium metal or maganese metal vapour
whith a titanium compound and a halogen donor.
The products deriving from the copolymerisation of
ethylene alone with the polyunsaturated compound are in the
form of crystalline polymers.
The applicant knows of the existence of various
processes for preparing crystalline copolymers deriving from
the polymerisation of ethylene with a conjugated or non-
conjugated polyolefine, and in particular butadiene and
ethylidene-norbonene (see for example Canadian Pat. N
1.043.943, Pat.Nl.046.697, Pat.Appln. N282.224).
These processes are based on vanadium-based
coordinated anionic catalysts which,-although giving high
polymerisation yields, do not attain catalytic activity levels
such as to obviate the need for the difficult purification
of the copolymer from the transition metal residues, which
damage the oxidation stability of the copolymer, and which
produce an undesirable colour. The applicant is also aware
of the Canadian Pat. Appl. N270.122 relating to a catalytic
composition which is extremely active in polymerising and
copolymerising mono alpha-olefines, and is prepared by
reacting an organometallic compound of group III of the periodic
system with a composition prepared by i) vaporising or
subliming magnesium under vacuum, and ii) condensing this
vapour into a condensed phase comprising a titanium tetrahalide
~6(~2~6à
and a halogen donor.
The same patent application states that the activity
of the catalytic composition in the homo and copolymerisation
of ~-olefines is extremely high when the quantity of magnesium
metal vaporised is such as to give an atomic Mg/Ti ratlo mueh
exceeding 0.5 in the condensed phase, and a eompound is present
therein which is able to yield up halogen to the ma~nesium
metal in excess of the atomic Mg/Ti ratio of 0.5 corresponding
to the complex MgX2.2TiX3 (X = halogen). In this manner, there
is further formation of MgX2, which interacts with the stoiehio-
metrie complex to give a new and more active eomplex containing
titanium. We have now discovered that by suitably modifying
the magnesium vaporisation conditions and choosing the reagents
and reaction conditions, it is possible to eopolymerise ethylene,
either alone or in mixture with other alpha-olefines, with a
compound eontaining one or more unsaturated olefine bonds, to
give highly crystalline polymers if ethylene is used alone.
Manganese can also be
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06
- used for preparing the catalytic composition, in addition to
magnesium.
Thus, the present invention pxovides a catalyst
effectiye in the high-yield copolymerization of ethylene or a
mixture of ethylene and another ~-olefin with a polyolefin
selected from the group consisting of cyclic and alicyclic
hydrocarbons containing more -than one double bond, optionally
conjugated, comprised of (1) a composition prepared by reacting
a metal vapour with a titanium compound and a halogen donor,
said metal vapour being selected from magnesium metal vapour and
manganese metal vapour, and (2) an organometallic compound oE
group III of the periodic table,where.in said magnesium metal is sublimed
under a vacuum between 2 and 10 ~ Torr and at a temperature
between 300 and 650C, and said manganese metal is sublimed under
a vacuum between 10 1 and 10 ~ Torr and at a temperature between
800 and 1100C.
In particular, the present invention provides a
catalyst effec-tive in the high-yield copolymerization of
ethylene or a mixture of ethylene and another ~-olefin with a
polyolefin selected from the group consisting of cyclic and
alicyclic hydrocarbons containing more than one double bond,
optionally conjugated, comprised of (lj a composition prepared
by reacting a metal vapour with a titanium compound and a
halogen donor, said metal vapour being sel~cted from magnesium
metal vapour and manganese metal vapour, and ~2) an organoalu~
minium compound, wherein said magnesium metal is sublimed under
a vacuum between 2 and 10 4 Torr and at a temperature between
300 and 650C, and said manganese metal is sublimed under a
vacuum between 10 1 and 10 4 Torr and at a temperature between
800 and 1100C. `
The present invention in another aspect also provides
in a process for the high-yield copolymerization o~ ethylene
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or a mixture o~ ethylene with another ~- olefinewit~ a polyolefine
selected from the group consis:ting o~ cyclic and alicyclic hydro-
carbons containlng more than one double band, optionally conjuga-
ted, which comprises contacting the comonomers with a catalyst as
defined above. In accordance with this process, ethylene may be
copolymerized with 1,3-butadiene or with ethylidinenorbornene
(5-ethylidine(2,2,1)-bicyclohepta-2-ene). The polymerization
reaction may be carried out in the presence of an inert solvent;
- the inert solvent may be the same as used for preparation of
compon.ent (1) for the catalyst. The polymerization may be carried
out at a temperature in the range between ambient tempexature and
a temperature slightly less than the melting point of the copolymer
and at a pressure of 1 to 30 atmospheres . The pol~merization
may for example be carried out at a temperature between ~0 and
120C and at a pressure of between 1 and 20 a-tmospheres. The
comonomers may be fed in a gaseous state to the catalytic
system in the absence of solvents. The catalytic composition
may be disposed on an inert support.
The activity of the catalytic system heretofore
described in such as to produce a quantity of copolymer per g
of titanium which is equal to or greater than 50 kg. The
catalytic composition can be prepared by vaporising the
magnesium or manganese either in their metal state or in the
form of one of their alloys, and condensing the vapour into a
cold solution prepared by dissolving a titanium compound and
optionally a halogenated compound in a diluent, ~e.g. an inert
diluent). The diluent may be an inert solvent selected from
the group consisting of aliphatic or aromatic hydrocarbons.
The metal (M) can be used in powder form, in the form
of granules or in lumps, and is preferably vaporised under
vacuum by sublimation.
As indica-ted above in the case of magnesium, for a
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~ A;l 6~ZOG
pressure of between 2 and 10 Torr, th.e temperature.ya~ries,.as
a function. of this latter, between:ahout.650 and 300C.
Manganese as indica.ted above requires more severe
conditions, namely 800-1100C for 10 -10 Torr.
If the operation is carried out at a higher tempera-
ture, the metal can be vaporised from its molten state even at
atmospheric pressure. The solution into which the vapour is
condensed is kept strirred at low temperature. In relation to
the solvent used, this can be fixed in the range o~ -120 to
0C, and generally -80 to -20C. The use of an inert diluent,
chosen from low volatility hydrocarbon solvents of low freezing
point (e.g. n-heptane, n-octane, toluene, etc.) is not s-trictly
necessary, as the reaction can be carried out even within the
titanium compound and the halogenated compound in their pure
state.
The titanium compound may be selected from the halides,
alcoholates and organometallic derivatives of trivalen-t and
tetrav~alent titanium.
The halogen donor may be selected from organic and
. 20 inorganic halides, e.g. alkyl halides. In par-ticular, organic
halogen donors may be selected from chloroalkanes, bromoalkanes,
chloroarenes and bromoarenes.
Titanium tetrachloride represents a liquid titanium
corpound sultable
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.
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for this purpose, and the alkyl halides are suitable as the
halogenated compounds, their measured excess then constituting
the reaction medium.
Examples of alkyl haIides which can be used are 1-
chlorobutane, 1-chlorohexane, and l-bromohexane, but secondary
or tertiary alkyl halides and aryl or alkylaryl halides are
also reactive. Of the inorganic halides, the most suitable
have proved to be SnC14, SbC15, GeCl~ and POC13.
Of the titanium compounds, in addition to the tetra-
chloride, effective use can be made of the other halides,
including the trivalent halides, the alcoholates`~ halogen
alcoholates, chelates and all the organometallic derivatives.
In practice, any titanium compound can be used, the difference
between them being only the rate oE reaction.
The M/Ti ratio to be obtained in order to prepare
extremely active catalytic compositions exceeds 0.5, and in
particular > 4. The preEerred value for said ratio i9 between
15 and 30, and a further excess of M (Mg or Mn) does not con-
stitu-te an advantage. The quantity of the halogen donor
compounds present in the reaction is adjusted according to the
quantity of M, with respect to which it should be in a ratio
of > 2 in the case of mono-halogenated organic compounds, and
> 1 in the case of inorganic compounds able to yield up more
than one halogen atom per molecule. The reaction between the
M vapour, the Ti compound and the halogenated compound already
partly takes place at the aforesaid low temperature. For its
completion, either a lonc~ period ~some days) of standing at
ambient temperature is required, or, preferably, heating for
a few hours (1-5), according to the chosen temperature
(50-180~C). The reaction is faster when the halogen donor
is inorganic.
The halogen donor is not strictly required in the
'~1 .
6~0~
low temperature-maintained solu-tion into which the metal
vapour is condensed. It can be added later, but before
the solution is raised to a higher temperature for completing
the reaction.
The fine suspension prepared as heretofore described
is usually used directly as the catalytic component for the
polymerisation, which will be described hereinafter, provided
neither any excess of one of the reagents nor any reaction by-
products substantially constitute disturbing agents in the
formation of the catalyst. AIternatively, said suspension can
be filtered and the solid resuspended in the dispersing agent
considered most suitable, generally the same in which the
polymerisation is carried out. Again, the solid compound can
be dispersed on an inert solid support, constituted for example
by the actual polymer which is to be produced.
As stated, the other catalytic componen-t is constituted
by an organometallic compound of an element of the III group
of the periodic system.
Of said elemen-ts, aluminium is that mostly used
for reasons of effectiveness and convenience.
Examples of compounds used are the trialkyl and
triaryl aluminiums such as Al(C2H5)3, Al(i-C3H7)3, Al(C6H5)3,
the alkylaluminium hydrides such as Al(H) li-C3H7)2, and
the alkyl and arylaluminium halides such as Al~C2H5)2Cl and
( 2 5) 2
The trialkyl derivatives are preferred, but they are
also very effective in mixture with the halogenated derivativès.
The molar ratio of the organometallic compounds to the
titanium compound must exceed 3 in order to attain maximum
specific activity.
For practical reasons, said ratio is kept very high,
for example between 100 and 500, in consideration of the fact
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that extremely small quantities of the titanium
compound are used in polymerisation. As stated, the copolyme-
risation process according to the present invention is based
on the copolymerisation of ethylene with a conjugated or non-
conjugated polyolefine, and uses the aforesaid catalytic
components in the presencè of an inert diluent, at a temperature
of between 40 and 120C and an operating pressure of between
1 and 20 Kg/cm2.
In batch tests, the reagents are fed into the reactor
such that the catalyst either forms in the presence of the
mixture of the two monomers or comes into contact with it.
In practice, there are two methods of operation,
both of which are effective. In the first, the catalytic
component containing the titanium is introduced last, while
in the second the reaction between the catalytic components to
be added successively to the monomer mixture is carried out
separately. In this latter case, there is a precontact time
which, although not critical should not be very prolonged, in
particular when a high Al/Ti ratio is used.
The aliphatic hydrocarbons are preferably used as
the inert diluents. However, the presence of a diluent is
not strictly necessary during the polymerisation stage, as it
is possible to operate in the gaseous state by introducing the
catalyst dispersed in a little low boiling solvent.
The monomers which the applicant has chosen for exempli~fiying
the copolymerisation process are those listed below. The
conditions detailed heretofore are absolutely general, and all
types of ethylene copolymers can be prepared by applying the
method of the present patent applica~ion, on the basis of the
detailed teachings for the copolymers listed hereinafter,
without leaving the scope of the invention. The expert oE
the art will be able to choose the most suitable operating
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conditions in relation to the required polymer.
The monomers are ethylene on the one hand, and
a cyclic or acicyclic hydrocarbon containing more than one
unsaturated bond, which can be conjugated, on the other.
Prototypes o~ these elasses oE hydroearbon preferred
for their reactivity and low cost are 1,3-butadiene and 5-
ethylidene-(2,2,1)-dieyelohepta-2-ene (ethylidenenorbonene).
They have a reactivity under polymerisation whieh
is less than that of ethylene, because of which they are fed
in excess (50 times or moxe? over the ~uantity of the same
monomer which it is required to obtain in the copolymer.
This exeess is utilised by reeyeling its solution~
The practically useful ethylene eomonomer present in
the eopolymer is ~ust a few per cent (less than 10 mol %).
The molecular weight of the eopolymer can be controlled
by lntrodueing hydrogen, in addition to varying the reaction
conditions. The copolymers prepared by the proeess aceording
to the present invention have properties which vary with their
composition. The ethylene-butadiene eopolymers contain trans
unsaturated bonds, while cis and vinyl unsaturated bonds are
absent or practically absent, as shown by a 1,4 trans addition
of the butadiene units. The ethylene-butadiene eopolymers rieh
in ethylene are charaeterised by densities between 0.9~0 and
0.960, melting points around 130C and an unsaturated bond
distribution as shown by the aecompanying 13C-NMR spectrum
(relative to a eopolymer eontaining 12.3 mol % of butadiene),
in which three peaks can be seen attributable to differently
struetured butadiene units along the polymer chain (peaks
attributable to methylenes in the bu-tadiene~at a = 32.6,
b = 32.7, and c = 32.9 ppm~. It should be noted that analogous
eopolymers prepared by the said art show only -two of said three
peaks in the C-NMR spec-trum. It is knownthat crystalline
poly alphaolefines such as polyethylene, isotactic polypropy-
lene, isotactic polybutene-etc. have been available commercial-
ly for some time.
These polyalphaoleEines are constituted either by
homopolymers or by copolymers with small quantities of a
second alphaolefine in order to solve certain technical problems.
The quantity of the second olefine is normally so
low as not to excessively reduce the crystallinity with respect
to the homopolymer, as certain important mechanical character-
istics such as the modulus, ultimate tensile strencJth ètc.
are associated with -the high crystallinity.
In copolymers of ethylene with butadiene, the
compatibility of units of the two types in the same crystal
enables substantially crystalline polymers to be obtained
over the entire range of compositions from pure polyethylene
to pure trans polybutadiene. In this case, there is therefore
not the limitation which exists in the case of copolymers of
-the monoalphaolefines, in which an olefine must be contained
in a very small quantity in the copolymer in order to maintain
crystallinity at a high level. An extremely important advantage
of the copolymers prepared according to the process of the
present patent is related to the fact that they contain
unsaturated bonds (either in the main chain as in the case of
butadiene, or in the side groups as in the case of ethylidenenor-
bonene).
By means of these unsaturated bonds, the copolymer
can be easily cross-linked (with sulphur or other reagents)
to further improve its technical characteristics such as thermal
resistance, impact strength or resistance to agents which
induce the formation of environmental stress cracking.
The unsaturated bonds also allow certain transforma-
tions which wouId otherwise be difficuIt if not impossible,
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such as foaming and the thermoforming of sheets.
EXAMPLE 1
The catalytic co~ponent containing titanium is
prepared in a 1 litre horizontally disposed rotating glass
~lask, at the centre o~ which is placed an aluminium crucible
heated electrically by means of a tungsten filament.
240 ml of n-heptane and 0.2 ml of TiC14 were placed
in the flask and 0.9 g of magnesium shavings were placed in
the crucible. The solution was cooled to -70C.
After putting the rotating apparatus under vacuum
(10 3 Torr), the crucible was heated by applying an electric
voltage across the ends of the filament of suE~icient intensit~
to heat it to red hea-t.
Vaporisa-tion of the Mg led to the formation of a brown
suspension, to which n-butyl chloride (l-chlorobutane, 8.2 ml)
was added after nullifying the vacuum by introducing nitrogen.
The suspension was then heated for 3 hours at
80C, using a reflux condenser.
Copolymerisation
A stainless steel autoclave having a capacity of 5
litres and fitted with a mechanical stirrer and controlled
electric heating was put under vacuum,.and a prepared solution
consisting of:
anhydrous n-heptane 2200 ml
butadiene 200 g
~l(C2H5)3 15 mmoles
was then introduced by suction.
The temperature of the autoclave was controlled at
70C before feeding hydrogen and ethylene into it at partial
pressures of 3.5 and 4.5 Kg/cm2 respectively.
10 ml of the heptane suspension prepared as
heretofore described and containing 0.075 mmoles of titanium
~6~2(~6
.
were fed into the autoclave, with an ethylene overpressure,
using a 100 ml steel phial provided with a feed valve and
discharge valve.
A heptane solution (50 ml) of Al~C2H5~C12 (7.5 mmoles)
was then added during the first five minutes of reaction to the
mixture already presen-t in the autoclave, using a piston
pump.
An immediate absorpti.on oE ethylene was observed, and
this was fed continuously so as to maintain the initial pressure
constant at a temperature of 70C.
After 3 hours it wa.s found that the ethylene was
still absorbed with an intensity approximately equal to the
initial intensity. The tes-t was however interrupted, and the
suspension contained in the autoclave was discharged and
:Eiltered.
388 g of dry polymer were obtained, having a MFI2 16
of 49.5, a butadiene unit content (moles~ of 3.3% and a melting
point (Tm), determined by differential thermal analysis, of
131C. The polymer, which had the appearance of a white solid
very similar to the appearance of a polyethylene, was mixed
with the following compounds (g per 100 g of polymer):
zinc oxide 5
stearic acid
2,2'-methylene-bis(~-methyl-terbutylphenol) (AØ2246)
N-oxydiethylbenzo-thioazole-2-sulphenamide (NOBS special) 1.5
dibenzothiazyl disulphide (Vulkacit DM)(Trademark~ 0.5
sulphur 3
The mixture was treated in a press at 180 for
30 minutes, to give a product having 40% of residue after
extraction with boiling xylols (the polymer as such was
~ completely so].uble).
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EXAMPLE 2
A test was carried out at 85C using the autoclave
and method described in example l.
In this case, the partial pressures of ethylene
and hydrogen were 5 and 3 Kg/cm2 respectively, and 250 g of
butadiene was introduced.
All the other quantities were as in example 1.
After 3 hours of polymerisation, 250 g of dry copolymer
were obtained having the following characteristics: butadiene
its = 3 3% (moles), MFI2 16 = 0.84 MFI21.6/ 2.16
melting point - 129Cr impact strength = 13.7 Kg/cm2.
When cross-linked as described in example 1, the
product obtained had an impact strength of 50.4 Kg/cm2.
EXAMPLE 3
A polymerisation test was carried out employing the
same apparatus and method of the preceding examples, using
the following reagents:
- n-heptane 1840 ml
butadiene 102 g
Al(C2H5)3 17.6 mmoles
H2 3.5 Kg/cm2
ethylene 5.0 "
Ti complex (see ex.l) 0.06 mmoles
The autoclave was maintained at 85C both during
gas introduction and during polymerisation, in the course of
which the consumed ethylene was made up.
After 4 hours the test was interrupted, and the
product was filtered off and dried, to give 285 g.
Analysis gave the following results:
butadiene units = 1.5% (moles), MFI2 16 = 0 99 g/10 min.,
MFI21 6 = 27-4, Tm (DSC) = 133C
~ .
~L~6~ 2~6
EXAMPLE 4
A solution prepared from 400 ml of n~heptane and ~0
ml of bicyclo(2,2,1)-5-ethyledine-2-heptene ~ethylidenenor-
bornene) was sucked into a stainless steel autoclave o-~ the
type described ln examplc 1, but l~aving a capacity o~ 2
litres.
The autoclave was temperature controlled at 85C,
and ethylene and hydrogen were then introduced at partial
pressures of 5 and3.;Kg/cm2 respectively.
The catalyst, consisting of a heptane suspension of
the product obtained by reacting 5 mmoles of Al(i-C4~19)3
with 0.012 mmoles of titanium in the form described in example
1 or 60 minu~es at ambient temperature, was then introduced
using a steel phial and a N2 overpressure.
The test lasted for one hour, during which the
consumed ethylene was made up so as to maintain its partial
pressure constant. The solid product obtained by filtering
the suspension`and drying weighed 35 g.
It had the following characteristics: 3.3% of
ethylidenenorbornene (weight), MFI2 16 = 3 4 g/10 min.,
MFI21 6 = 33~ =-0.9633 g/cm3.
EXAMPLE 5
The catalytic component containing titanium was
prepared in a manner similar to that described in example 1,
but start.ing from the following reagents:
l-chlorooctane 120 ml
TiC14 0.088 ml
manganese metal . 1.5 g
The solution was cooled to -50 and a vacuum of
10 4.Torr applied, after which the manganese was vaporised
and condensed. A dense dark brown-suspension was.obtained,
which was.then heated to 100C for one hour.
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~6~2~G
Chem.ical analysis showed that the homogenised
suspension contained 5.10 mmoles/l of Ti, 186.2 mmoles/l of
Mn, 390.0 mmoles/l of Cl.
Copolymerisation
A copolymerisation test between butadiene and
ethylene was carried out using the apparatus described in
example 1.
The solution fed into the reactor was prepared from:
n-heptane 2200 ml
butadiene . 250 g
Al(i-C4Hg)3 22.5 mmoles
After controlling the. temperature at 85C, the
autoclave was pressurised with 3 Kg/cm2 of hydrogen and 5
Kg/cm2 of ethylene.
. 15 cm3 of the suspension containing the titanium
complex prepared as here-tofore described were then introduced.
Further ethylene was added for 3 hours in order to maintain
the pressure at the initial value of 10 Kg/cm2 at 85C, after
which the test was interrupted, and the product filtered off
and dried.
200 g of polymer were obtained having the following
characteristics: 1,4 trans butadiene units 5.15% tmoles),
MFI2 16 = 0 05 g/10 min., Tm (DSC) = 132C, ¦ n ~ (in decalin
at 105) = 1.75.
EXAMPLE 6
The catalytic component containing titanium was
prepared in an apparatus analogous to that described in
example 1, from:
n-octane 300 ml
TiC14 0.187 ml
SnC14 8 ml
Mg metal 1.2 g
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zo~
The magnesium was vaporised at 5.10 Torr and
condensed into the solution, which was maintained at about
-50C-
The suspension obtained was raised to ambient tempera-
ture. Af-ter 24 hours, the solution lying above the decanted
solid was free from titanium, whereas the homogenised suspension
contained 6.32 mmoles/l of Ti, 187 mmoles/l of Mg, 207 mmoles/l
of Sn and 863 mmoles/l of Cl.
Copolymerisation
The test was carried out in the autoclave described
in example 1 at 85C, using the same method and the same
reagents as example 5, with the exception of the catalytic
component containing titanium, which this time consisted of
11.85 ml of the aforesaid suspension. The polymer obtained
weighed 180 g and showed the following properties:-MFI2 16 =
0.1 g/10 min., Tm = 131C (DSC), butadiene units = 3.34%
(moles).
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