Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-03-30
2002-03-12
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S232000, C525S240000
Reexamination Certificate
active
06355731
ABSTRACT:
This invention concerns a process for the preparation of a thermoplastic elastomeric polyolefin composition through the polymerization of CH
2
═CHR olefins, where R is selected from H and an alkyl radical with 1-8 carbon atoms. More precisely, this invention concerns a process for the sequential polymerization of the olefins carried out in the presence of catalysts belonging to different classes in the various stages. Moreover, this invention concerns the polymer compositions obtainable with said polymerization process.
Sequential polymerization processes for the preparation of heterophasic polyolefin compositions with both thermoplastic and elastomeric properties are already know. One such a process for the production of the above mentioned compositions is described, as a way of example, in patent application EP-A-400333. Said compositions, which contain a crystalline polyolefin fraction and an elastomeric polyolefin fraction, are produced by way of polymerization in the presence of Ziegler-Natta catalysts.
Also known are processes for the sequential polymerization of olefins carried out in at least two polymerization stages, where the first polymerization occurs with a Ziegler-Natta catalyst, and the second polymerization, started after the deactivation of the Ziegler-Natta catalyst, occurs with a metallocenic catalyst. One such a process is described, as a way of example, in international patent application WO 96/11218. The process described leads to the production of a polymer composition comprising a crystalline polyolefin fraction and an elastomeric polyolefin fraction.
Also know are processed for the sequential polymerization of olefins carried out in at least two polymerization stages, where the first polymerization uses a Ziegler-Natta catalyst, and the second polymerization, started after the deactivation of the Ziegler-Natta catalyst, uses a metallocene catalyst. One such process is described, for example, in international patent application WO 96/11218. The process described produces a polymer composition comprising a cystalline polyolefin fraction and an elastomeric polyolefin fraction.
A multi-stage sequential polymerization process has now been found where one can produce in distinct and subsequent stages two different fractions of elastomeric polymers; with said process, in fact, the second fraction is produced in the total absence of the catalyst that produces the first elastomeric fraction. In this manner it is possible to obtain heterophasic polyolefin compositions containing, in addition to the crystalline polyolefin fraction two different elastomeric polyolefin fractions, one produced solely with Ziegler-Natta catalysts, and the other only with catalysts containing a &pgr; bond, such as metallocenic catalysts.
Moreover, thanks to the process of this invention the heterophasic composition is free of undesired effects that are inevitably present when the deactivation of the Ziegler-Natta catalysts stage is not carried out.
Therefore, this invention provides a process for the preparation of a heterophasic polyolefin composition comprising:
i) polymerizing, in any given order,
a) monomers selected from the group consisting of:
(1) propylene, whereby a crystalline propylene polymer that is at least 80% by weight insoluble in xylene at ambient temperature is formed,
(2) propylene and ethylene,
(3) propylene and a C
4
-C
10
&agr;-olefin,
(4) propylene, ethylene and a C
4
-C
10
&agr;-olefin, whereby a crystalline propylene copolymer containing more than 85% by weight of propylene is formed,
(5) ethylene, whereby an ethylene homopolymer is formed, and
(6) ethylene and a C
3
-C
12
&agr;-olefin, whereby an ethylene copolymer containing up to 20% by mole of the C
3
-C
12
&agr;-olefin is formed, and
b) copolymerizing ethylene and a C
3
-C
10
&agr;-olefin, and, optionally, a diene, to form an elastomeric copolymer partially soluble in xylene at ambient temperature, containing up to 70% by weight of ethylene in the fraction soluble in xylene at ambient temperature, wherein the polymerizations are carried out in the presence of a Ziegler-Natta catalyst (1) obtained by contacting the following components:
(a) a catalytic component containing a titanium compound and an electron-donor compound, both supported on Mg chloride;
(b) an organometallic compound, and, optionally,
(c) an electron-donor compound;
ii) contacting the polymer obtained in (i), in any given sequence, with:
a) a compound capable of deactivating the catalyst present in (i); and
b) a catalyst (2) obtained by contacting:
(I) a compound containing a transition metal M, and at least one ligand coordinated with metal M by a &pgr; bond, and
(II) at least one cocatalyst; and
iii) copolymerizing ethylene and a C
3
-C
10
&agr;-olefin in the presence of the polymer treated as in (ii), and the catalyst (2).
For the purpose of this patent application by ambient temperature is intended a temperature of about 25° C.
The solubility in xylene is determined according to the method indicated below.
The quantity of ethylene fed during the copolymerization stage (iii) is such that the percentage by weight of ethylene with respect to the total monomers in the copolymer produced in this manner varies preferably from 30 to 80%, more preferably from 50 to 75%. A preferred process of this invention is the one where 20 to 45% by weight of the polymer matrix (1) is produced in stage (i).
An especially preferred process of this invention is the one where in stage (i) (b) an elastomeric copolymer is produced whose fraction soluble in xylene contains up to 40% by weight of ethylene. Moreover, the preferred process of this invention is the one where in stage (i) (b) the fraction of copolymer insoluble in xylene at ambient temperature is from 1 to 15wt% with respect to the whole polymer produced in stage (i).
The polymers produced in stage (i) of the process of this invention are prepared in two or more polymerization phases using, from the above mentioned known Ziegler-Natta catalysts, those that are extremely stereospecific. Examples of said catalysts are described in European patent EP 45 977, and in U.S. patents 4,339,054, 4,472,524, and 4,473,660.
The solid catalyst components used in these catalysts comprise, as electron-donor compounds, the ones selected from ethers, ketones, lactones, compounds containing N, P, and/or S atoms, and mono- and dicarboxylic ester acids.
Particularly suitable are the phthalic acid esters, such as diisobutyl-, dioctyl-, diphenyl phthalate, and benzylbutyl phthalate.
Other particularly suited electron-donors are the 1,3-diethers of formula
where R
I
and R
II
, equal or different from each other, are alkyl, cycloalkyl, or aryl radicals with 1-18 carbon atoms; R
III
or R
IV
, equal or different from each other, are alkyl radicals with 1-4 carbon atoms, or 1,3-dieters where the carbon atom in position 2 has a cyclic or polycyclic structure containing 5, 6, or 7 carbon atoms, and two or three unsaturations. Ethers with such a structure are described in published European patent applications EP-A-361493, and 728769. Examples representative of said compounds are: 2-methyl-2-isopropyl-1,3-dimethoxypropane, 2,2-diisobutyl-1,3-dimethoxypropane, 2-isopropyl-2-cyclopentyl-1,3-dimethoxypropane, 2-isopropyl-2-isoamyl-1,3-dimethoxypropane, and 9,9-bis(methoxymethyl)fluorene.
The preparation of the above mentioned catalyst components is carried out in various methods. For example, a MgCl
2
. nROH adduct (particularly in the form of spherical particles) where n generally ranges from 1 to 3, and ROH is ethanol, butanol, isobutanol, is caused to react with an excess of TiCl
4
containing the electron-donor compound. The reaction temperature generally ranges from 80 to 130° C. The solid is then isolated and made to react one more time with TiCl
4
, optionally in the presence of the electron-donor compound, and is then separated and washed with a hydrocarbon until all the chlorine ions have disappeared.
The titanium compound, expressed as Ti, in the solid catalyst component is generally present in a percentag
Covezzi Massimo
Govoni Gabriele
News Jean
Montech USA Inc.
Nutter Nathan M.
LandOfFree
Process for the production of heterophasic polymer... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for the production of heterophasic polymer..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for the production of heterophasic polymer... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2878506