Note: Descriptions are shown in the official language in which they were submitted.
S~3
This invention relates to an improved me-thod for
the polymerization and the copolymerization of mono~o:Lefins
and diolefins, which method employs a novel catalyst system
permitting to obtain a hlgher yields of stereospecific
polymers as compared with the known systems.,
~t is known to polymerize unsa-turated compounds by
means of binary catalysts composed by compounds of transition
metals together with aluminum-alkyls or hydrides. More
particularlyr the present Assignee is the owner of many
patents and patent applications related to the polymerization
of such compounds by means of systems based on derivatives
of tra~sition metals in union with poly-imino-alanes (PIA).
Among many others, systems have been disclosed
which are comprised of TiC14 and compounds resulting from
the repetition of unions of the kind (H A1 NR) in which R
is a hydro-carbonaceous radical, compounds which are cha~
racterized by a molecular cage-Iike structure the steric
configuration of which is a func-tion of the number of iminic
units.
We have now surprisingly found that the addition
of aluminum alkyl-, or hydride-, derivatives (A) to the
binary system compri5ed of the compound of the transition
metal (B) and poly-imino alane (Cl permits to prepare
ternary catalysts for the polymerization of mono- and
diolefine, which are much more active than the catalysts
composed by the couples AB or BC. More particularly, A
is a compound of the formula Al R3_XHx in which R is a
hydrocarbonaceous radical and x is a number ranging from
0 ~o 3.
The same Assignee hereof is the owner of the Canadian
Patent Application No. 269.333, filed on 7.1.1977 relating
to a method for the modification of the PIA, consisting in
-2- ' ~
causing PIA to react wlth aluminum alkyls with molar
ratios between the iminic units ~1-I Al NR) and the aluminum
alkyl comprised between l and 3.
The react.ion according to the above ci-ted can be
reproduced by -the following pattern:
(H Al NR)n ~ ~ Al R'3 -> ~(R' Al NR)z ~H Al NR)n-
Al R3_x Hx (l)
(I)
wherein n indicates the number of repeating iminic units, R
and R' are hydrocarbonaceous radicals, equal or different
from each other, z is equal to the product y~, z varying .
Erom l to n and x having.the above indicated values. Compounds :
are obtained, derived from the parti.al or total replacement
of the hydride hydrogens oE the PIA by alkyl groups with
retention of the typical cage-like molecular structure,
together with hydride derivatives of aluminum having the
composition
Al R3-x ~x
As the quantity of al.uminum alkyl is increased, the
reaction is conducive to the formation of derivatives (I)
having an increasing number of alkyl radicals bound to aluminum
until obtaining PIA derivatives in which all the hydride atoms
have been replaced by alkyl radicals.
The use of quantities of (H Al NR)n in excess over
the aluminum alkyl in the reaction indicated above encourages
the formation of simple hydride derivatives of aluminum, such
as AlR2H, AlRH2, AlH3 andt more particularly the hydrogen-
richer species.
The interaction of the latter species, or of the
aluminum alkyls themselves with PIA moleculaes is responsible
for the formation of species which, in union with the transition
~. :
65~3
metal, give rise to catalysts endowed with a stro~yer catalytic
activity. This fact, which ulfils the requirements oE the
present invention, has been ascertained by us on the basis of
the following facts:
1. The results which have been obtained in poly-
merization tests of isoprene with the ternary
systems indicated above, in comparison.with the
binary systems PIA-TiC14 and A1~3-TiCl~, indicate
that the improved activity displayed by the tern-
ary systems can be attributed to particular
interaction compound of PIA with Al R3 or with
AlR3 XHx. The results are plotted in FIGURE 1
in which the solid polymer yield is reported on
the ordinates as a function of the molar ratio
Al/Ti on the abscissae.
IN FIGURE 1 the curves are referred to A-TiC1
AlEt3, B-(H Al N-isoPr)6 ~ Ti C14, and
C- ~H Al N-isoPr)6 ~ Al Et3.
The same result has heen obtained in the poly-
merization of ethylene wi-th the ternary systems
TiC13-PIA-AlR3 as compared with the binary
systems TiC13-PIA, and TiC13-AlR3~ The results
are tabulated in TABI,E 2.
2. An activating effect due to the replacement of
the hydride hydrogens of the PIA by alkyl groups
is to be excluded, inasmuch as the totally or
partially alkylated PIAs have proven. to be much
less active than the starting PIAs, or even
inactive in the polymerization of isoprene in
union with TiCl~.
3. An improved polymerization activity towards
isoprene has been observed, relative to the PIA,
- 4
.~ .
~v~
wi-th products (II) obtained hy subsequent
chlorination of PIA and treatment with LiAlH~.
In agreement with the reactions 2 and 3 such
treatments correspond to the Eormation o~
complexes of PIA with AlH3.
(H Al NR)6 ~ H Cl C(Cl Al NR) (H Al NR)5 J (2)
~ ( Cl Al Nr) (H Al NR)5 J + Li ~l H4 (H Al NR)6.Al H3+
LiCl 13) (II)
FIGUR~ 2 refers to the activity increase as observed
for the product IX with respect to the starting PIA: the
FIGURE reports the solid polymer yield plot, in ordinates, as
a function ~
~ . .
,~, .
oE the A1/Ti ratio ol~the abscissae.
In saicl FIGUR~ 2 tile cur~es are reEerre~, respec-
tively, to A - (ll Al N-isoPr)6.AlH3 ~ TiCl~
B - (ll Al N isoPr)6 ~ TiC~4
The polymeriza-tion runs can be carried out at a
temperature ranging from -50~ to ~250C and preferably in the
range from +10C -to 200C and under a pressure ranging from -the
vapor pressure of the monomer when the lat-ter is li~uid, to
200 atmospheres, the interval from 1 to 20 a-tmospheres being
preferred, possibly in the presence of a solvent selected from
among -the aliphatic, aromatic or cycloaliphatic hydrocarbons.
The interval of -the molar ratio A1/Me (in which
Al indicates the sum of the aluminums of the iminic units and
of the aluminums of the simple hydride or alkyl derivatives,
and Me is the transition metal), which ratio, as is known, has
an influence on the polymerization velocity and the yield of
solid polymer, can be varied from 0.1 to 500, the preferable
interval being varied consistently with -the nature of the
monomer which is intended to be polymerized.
Figure 3, wherein the yield oE solid polvmer is
reported on the ordinate as a function of khe Al/Ti molar
ratio on the abscissa, shows the results ob-tained in the polym-
erization of isoprene with a ternary sys-tem (curve A) in compar-
ison with a binary systern (curve B).
The present invention will be now further under-
tood by reference -to the Eollowing non restrictive examples.
EXAMPLES 1 ~ 15
FIGURE 1, in which the yield of solid polymer,
on the ordinates, is plotted as a function oE the ratio A1/Ti
(abscissae) comprises the results as obtained with the ternary
"'~
system (H Al N-iso-C3H7)6 - Al(C2ll5)3 TiC14, correspondi.ngly,
in par-ticular, to the molar ratio Al (C2ll5)3 :_1 (H Al N-iso
C3H7)6 ~ 0.02 in comparison with the resul-ts which have
ob-tained with binary systems (H Al N-isoC3H7)~ - Ti Cl4, and
( 2 5)3 ~
The polymeriza-tion runs have been carried ou-t
according to the following procedure :
A pop bottle which had previously been heated
. and cooled under a nitrogen stream is chargecl, the nitrogen
atmosphere being maintained, with anhydrous n-hep-tane (mls 90),
TiCl4 (0.64 millimol) and then Al(C2H5)3 or PIA, by adding,
or not, ~ -------- 7
~ .
- 5a -
~6~43
Al (C2H5)3 in the amount indicated, consistently with the
desired Al.lTi ratio. A brown preci.pitate is formed.
The reaction mixture is aged by shaking it for lO
minutes at room temperature and 20 grams of isoprene are
added thereto. ~he bottle is sealed and st:irred durlng 2
hours in a thermos-tatic bath at 30C. After that such a time
has elapsed, the polymerization is discontinued by adding
20 mls of methanol in which an antioxidant has been dissolved.
, The reaction mixture is poured in an excess of methanol and
the solid polymer is dried at 50C under vacuum, and weighed.
The polymer struc-ture is determined by infxared analysis and
the intrinsic viscosity at 30C in toluene is measured.
TABLE l reports the structure and the intrinsic
viscosity of polyisoprenes as obtained with the abo~e specified
ternary catalyst system.
EXAMPLES l6 - 35
FIGURE 2, in which the solid polymer yield is reported
on the ordinates as a function of the Al~Ti ratio on the
abscissae, comprises the results obtained in the polymeriza-
tion of isoprene with the (H Al N-isoC31I7)6. AlH3 - TiCl4
system as compared with those obtained with the (H Al N-.
iSoc3H7)6-Ticl4 system
These results confirm the improved activi-ty of the
species which result from the complex~forming of (H Al N-iso
C3H7)6 with simple alane derivatives.
The compound has been obtained with ~he following
procedure. By working in a nitrQgen atmosphere, to a solution
of (H Al N-isoC3H7)6 (9-5 millimols) in diethyl ether (60 mls)
there is added slowly a solution (mls 13.5) of ~Cl (9.5 milli-
mols) in diethyl ether. The reaction corresponds to the
average substitution of an atom of hydride hydrogen by a
chlorine atom according to the reac-tion pattern ~2) ~see
- 6 -
~L~at6S~3
S. Cucinella et al, JA Organometal. Chem.., 108, 13 (1976).
The product thus ob-~ained ~57.10 3 gram-atoms oE aluminum?,
in diethyl ether ~100 mls) has been supplemented by a solution
of LiAlH4 (9.5 millimols) in diethyl ether (12 mls).
According to the reaction pat-tern (3) a compound
II is formed, which has been separated by evaporating the
solution upon separation of LiCl by filteri.ng it off and dried
under vacuum (10 3 millimeters oE mercury cluring 8 hours at
room temperature~. ~
The chemical analysis indicates for the product which : .
has thus been obtained:
Al : N : HaCt ~ 1 : 0.87 : 1.25 :
The polymerization tests have been carried out
according to the procedure of EXAMPLES 1 to 15. Also in the
case of the System II-TiC14 the as-obtained polymer has a high .
contents of 1,4-cis and high values oE ~ n J- ~: -
. For example, the polymer obtained for an.~l~Ti of
1.15 has the following pro~erties : 1,4-cis : 95.8% i 1,4-tra~s
1.3% ; 1,2-unsaturations : 0% ; 3,4-unsaturations 2.9% ;
~ n J toluene = 5-20-
EXAMPLES 36 - 52
_
FIGURE 3, in wh1ch the yield of solid polymer,
ordinates, is reported as a function of the Al/Ti ra-tio,
abscissae, comprises the results obtained in the polymerization
of isoprene with the ternary system IH Al ~-isoC3H7)6- Al H
~isoC4Hg)2 - TiC14 ~curve A) in comparison with the binary
system (H Al N-isoC3H7)6 TiC14 ~curve B).
The polymerization tests have been carried ou-t
according to the procedure of Examples 1 to 27. The poly-
isoprene which has been obtained with the ternary system hasa high contents of 1,4-cis unsa-turations and high values of
. For example, the polymer which has been obtained
~3
wi-th an ~l/Ti = 1.20 has the Eollowin~ proper-ties:
l,4~cis : 95~6~ ' 1,4-trans : 0% ; 1,2 unsat. = 0.5% ;
3,4-unsat. = 3.8~ i total unsaturations O 102 ;
n ~ 30C = ~.6.
toluene
EXAMPLES 53 - 59
A 5 liter autoclave equipped with stirrer, has been
dried and deaerated by heating~it under vacuum and Eilled
up to ambient pressure with hydrogen and charged b~ siphoning-
10 in with 1,6000 mls of anhydrous nor.heptane. The temperature
is raised to 90C, whereafter there are charge 300 mls of
nor. heptane to which there have been added, in the order
given, TiC13 - AlPIA - Al Et3 in the quantities of TiC13
5 millimols, (Al.PIA + Al.~lE-t3) 15 millimols, with a variable
lAlEt3 : AlpI~ . On completion of the addition of the
catalyst hydrogen is charged until attaining a gauge pxessure
of 1.5 kilograms per sq. centimeter, then ethylene until
attaining a total pressure of 2.5 kilograms/sq. centimeter,
which is maintained constant with an æthylene stream adjusted
20 with a pressure-stat. The absorption of ethylene was checked ~;
continously with a flow-meter. After two hours of polymeri-
zation run the autoclave has been cooled, the gas vented and
the suspension dumped and centrifuged, and the polymer was
dried in an oven vacuum at 60C and finally weighed.
The results which have been obtained are collected
in TABLE 2 which shows the improved activity of the species
which contains AlEt3 more particularly with the 6 to 8~ molar,
both relative to the species having no AlEt3 and to that
resulting from the complex-formation of (H Al N-isoPr)6 with
simple alane derivatives in agreement with the reaction
patterns 2 and 3 (EXAMPLES 28-43).
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