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Title:
A METHOD FOR MANUFACTURING OLEFIN COPOLYMERS CONTAINING FUNCTIONAL GROUPS AND POLYMERS OBTAINED BY THE METHOD
Document Type and Number:
WIPO Patent Application WO/1996/034023
Kind Code:
A1
Abstract:
A method for the manufacture of olefin copolymers containing functional groups by polymerizing a 2-5 carbon atom olefin with a monomer containing a functional group, at an elevated temperature in the presence of a catalyst which polymerizes the olefin, by using metallocene catalysts.

Inventors:
AALTONEN PAEIVI (FI)
LOEFGREN BARBRO (FI)
SEPPAELAE JUKKA (FI)
Application Number:
PCT/FI1996/000222
Publication Date:
October 31, 1996
Filing Date:
April 23, 1996
Export Citation:
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Assignee:
BOREALIS AS (DK)
AALTONEN PAEIVI (FI)
LOEFGREN BARBRO (FI)
SEPPAELAE JUKKA (FI)
International Classes:
C08F4/642; C08F210/00; C08F210/02; C08F210/06; (IPC1-7): C08F210/00; C08F4/642
Foreign References:
EP0092070A21983-10-26
EP0552945A21993-07-28
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Claims:
Claims
1. A method for the manufacture of olefin copolymers containing functional groups by polymerizing a 25 carbon atom olefin with a monomer containing functional groups, at an elevated temperature and in the presence of a catalyst which polymerizes the olefin, characterized in that the catalyst used is a metallocene catalyst.
2. A method according to Claim 1, characterized in that the metallocene is selected from bis(nbutylcyclopentadienyl) zirconium dichloride, l,2ethylenebis(indenyl) zirconium dichloride and l,2ethylenebis(indenyl) hafnium dichloride.
3. A method according to Claim 1 or 2, characterized in that the polymerization is carried out using methyl alumoxane (MAO) as an activator.
4. A method according to any of the above claims, characterized in that the functional monomer is selected from2methyl3buten2ol, 2methyl3butenlol, 3methyl3buten lol and 5hexenlol.
5. A method according to any of the above claims, characterized in that the olefin is selected from ethylene and propylene.
6. Olefin copolymers containing functional groups, which copolymers have been prepared by a method according to any of the above claims.
Description:
A method for manufacturing olefin copolymers containing functional groups and polymers obtained by the method

The invention relates to a method for the polymerization of olefins and monomers ining functional groups.

The linking of monomers which contain functional groups to a hydrocarbon polymer chain signifies the creating of a usable method for the modification of the chemical and physical properties of olefins. By using monomers containing functional groups it is possible to improve properties such as adhesion, dyeability, printability and permeability. Furthermo¬ re, a functional group provides a possibility for graft copolymerization and thereby for uses such as compatibilization of blends containing poly olefins.

The Ziegler-Natta catalyst system is commonly used in the polymerization and copolyme¬ rization of olefins, but one of the major limitations of these conventional catalysts is that they are not suited for use in conjunction with monomers containing polar monomers. Ziegler-Natta catalysts rather form a complex with the electron pair of a heteroatom, and thus in polymerization they rapidly deactivate the active centers by forming a stable complex with the functional group. In other words, the catalysts are poisoned in the presence of functional groups.

Therefore the conventional method for the manufacture of olefins containing functional groups has been high-pressure polymerization by using free radical catalysts. In polymeri- zations of this type, it is possible to link highly different groups to olefins. The high- pressure process typically yields products having a low density.

An example which can be given of high-pressure processes for the manufacture of olefin polymers containing functional groups is EP 092070, in which the catalyst is peroxide and the polymerization is carried out at a pressure of 350-5000 bar. Patent applications DE 3227331 and DE 1185816 also relate to free radical polymerization at high pressure and temperature.

The more a polar compound resembles alpha-olefin, the greater its potential to be polymerized by the same active centers as olefins. In practice this non-desirable mutual interaction can be minimized by certain methods, such as (a) by isolating the double bond from the heteroatoms by means of a longer hydrocarbon chain; (b) by adding a steric barrier around the heteroatom; (c) by decreasing the electron donor character of the heteroatom, for example, by linking to it or in its vicinity a group which attracts elect¬ rons; (d) by selecting catalyst components which are inert to functional groups; (e) by precomplexing the functional monomer by using a Lewis acid; or (f) by using a polar solvent which becomes polarized with the active center but allows the polymerization of the vinyl monomer.

If deactivation can be successfully prevented by one or several of the above-mentioned methods, the copolymerization of functional monomers will become more popular than it is today.

US patent publication 5.286.800 discloses the polymerization of comonomers containing functional groups with alpha-olefins. In these polymerizations there are used borane monomers which are converted, by reactions after the polymerization step, into poly- olefins which contain functional groups.

In Japanese patent publication 61 72 447, the comonomer used is 10-undecen-l-ol which has been pretreated with tri-isobutyl aluminum for 3 hours at room temperature before polymerization.

An object of the present invention is to provide a novel method for the manufacture of copolymers of olefins and monomers containing functional groups. Furthermore, one object of the invention is a method in which the catalyst system has in the presence of a polar group as high an activity as possible. One object of the invention is also to provide a method for the copolymerization of olefins in which the copolymerization with a polar comonomer takes place in one step, without any pretreatment or after-modification. One further object according to the invention is the manufacture of functional polyolefins in which the molar masses remain relatively high and the molar mass distributions are wide.

According to the invention it has been observed that, if metallocene catalysts are used, it is, surprisingly, possible to polymerize olefins and monomers containing functional groups in one step and without any after-treatment.

Thus the method according to the invention for the manufacture of olefin copolymers containing functional groups by polymerizing an olefin containing 2-5 carbon atoms with a monomer containing a functional group, at an elevated temperature and in the presence of a catalyst which polymerizes the olefin, is characterized in that the catalyst used is a metallocene catalyst.

The olefin used in the manufacture of copolymers according to the invention consists of olefins containing 2-6 carbon atoms. Preferably, ethylene or propylene is used, but olefins having a longer carbon chain, such as 1-butene, pentene and 1-hexene, can be used just as well.

The catalyst used is a metallocene-type catalyst. The metallocene may be a metallocene of any type. Thus, suitable metallocene compounds are compounds having the formula (Cp) m R n MR' 0 X p , where Cp is an unsubstituted or substituted and/or fused homo- or heterocyclopentadienyl, R is a group containing 1-4 carbon atoms which serves as a link between two Cp rings, M is a transition metal belonging to group 4A, 5A or 6A (Hub- bard), R' is a C,-C 2 hydrocarbyl or a hydrocarboxy group, and X is a halogen, m being 1-3, n being 0 or p being 0-3, and the sum n+o+p corresponding to the state of oxidation of the transition metal M. The transition metal is preferably zirconium or hafnium, most preferably zirconium. Examples of suitable metallocene compounds include, among others, bis(n-butylcyclopentadienyl) zirconium dichloride, 1 ,2-ethylene-bis(indenyl) zir¬ conium dichloride, and 1 ,2-ethylene-bis(indenyl) hafnium dichloride.

The polymerization activity of the catalyst can also be enhanced using activators such as alumoxane. One method is to add the alumoxane to the metallocene compound before, simultaneously with, or after the metallocene. Another method is to introduce the activator directly into the polymerization reactor.

Suitable activators include alumoxane compounds having the formula R-(Al(R)-O) n -AlR 2

or (-Al(R)-O-) m , where n is 1-40, m is 3-40, and R is a C,-C 8 alkyl group. Preferably R is a methyl group.

The support used may be any porous or inert support, such as silica or alumina or mixtures thereof.

The polymerization can be carried out by any method, for example by slurry polymerizati¬ on or gas phase polymerization. Thus the polymerization may be carried out, for example, at a temperature of 60-100 °C and under a pressure of 1-100 bar. The partial pressure of olefin in the reactor may vary within a range of 1-3 bar and the amount of comonomer within a range of 0.5-10 mmol.

The invention is described below in greater detail with reference to the accompanying examples.

Materials

Bis(n-butylcyclopentadienyl) zirconium dichloride, l,2-ethylene-bis(indenyl) zirconium dichloride, l,2-ethylene-bis(indenyl) hafnium dichloride and methyl alumoxane (MAO) were all of a commercial grade and were not purified separately. The polymerization- grade ethylene and propylene, and the n-heptane and toluene serving as the medium were purified by feeding them via a column series to remove any residual moisture and oxygen. The comonomers 2-methyl-3-butenol and 5-hexen-l-ol were of a commercial grade and they were purified by drying and nitrogenation.

Polymerization

Ethylene copolymerizations were carried out in an autoclave of 0.5 dm 3 at temperatures of both 60 °C and 80 °C for 40 minutes, the reaction medium used being n-heptane.

The medium n-heptane (350 cm 3 ) was introduced into a vacuumized and nitrogenated reactor equipped with a stirrer. The rotation velocity of the stirrer was all the time 400

5 rotations per minute. The comonomer was added in one batch under nitrogenation, and the cocatalyst (MAO) (Al/M 4000 mol/mol, where M = Zr, Hf) was added at the beginning of the polymerization by using a pump. After the polymerization temperature had been reached, ethylene was fed into the reactor. Ethylene consumption was monitored by means of a mass flow controller. After equilibrium had been reached, polymerization was started by pumping the catalyst into the reactor. The partial pressure of ethylene or propylene was maintained constant (2.5 bar ethylene pressure) by means of an electronic pressure controller and a solenoid valve, and the reactor temperature was maintained constant. The conversion was maintained low in order that it could be assumed that the conversion in the reactor was constant. At 40 minutes, reactor pressure was released and the polymer product was washed with a solution of ethanol and hydrochloric acid and was dried.

The compositions of the copolymers of ethylene and functional monomers were deter- mined by using a JEOL NMR spectrometer. The melting points and enthalpies were determined from the peak of the DSC curve by using a Perkin Elmer DSC-7 instrument. The DSC measurements were carried out by reheating the sample to 180 °C at heating rates of 2 and 10 °C/min.

The molar masses and the molar mass distributions were measured using a Waters type ALC/GPC 150 instrument in which there had been installed 3 TOSOH mixed-bed columns in which the polystyrene barrier limit was 4 x 10 8 at a temperature of 135 °C. The solvent used was 1,2,4-trichlorobenzene having a flow rate of 1.0 ml/min.

Examples

Ethylene was copolymerized with various comonomers containing functional groups. The functional monomers used were 2-methyl-3-buten-2-ol and 5-hexen-l-ol. The catalyst used was a bis(n-butyldicyclopentadienyl) zirconium dichloride/MAO combination. The polymerization conditions and the properties of the product are shown in Table 1.

Table 1

Example Comonomer Comonomer Activity Molecular M M Λ T amount kg/g cat.h weight mmol M^IO 3

1 - 26.1 222 3.4 136.7

2 2-methyl-3- 1 22.3 150 3.7 137.2 buten-2-ol

3 2 16.2 183 3.1 136.0

4 3 10.6 177 3.4 134.2

5 4 8.3 183 3.1 135.6

6 m 5 6.1 161 3.8 135.9

7 n 6 5.2 172 3.7 134.7

8 5-hexen-l-ol 1 13.0 158 3.4 134.2

9 2 9.0 130 3.1 134.8

10 3 6.5 147 4.2 132.8

11 4 5.6 161 6.0 131.9

Examples 12-28

Propylene copolymerizations were carried out by the same procedure as the ethylene copolymerizations, except that the medium was used in an amount of 300 cm 3 , the polymerization time was 60 minutes and the polymerization temperatures were 30 °C and 60 °C, and the propylene overpressure was 3.0 bar. Both 1 ,2-ethylene-bis(indenyl) zirconium dichloride and l,2-ethylene-bis(indenyl) hafnium dichloride were used as cata¬ lysts. The results are shown in Tables 2 and 3.

Table 2 Catalyst l,2-ethylene-bis(indenyl) zirconium dichloride

Example Monomer Monomer amount Yield M» . M./M, mmol £

12 5-hexenol 1.01 18.7 30500 14800 2.06

13 1.69 8.4 27000 13500 2.00

14 2.96 5.4 25200 12100 2.08

15 3.38 2.6 22100 10200 2.17

15 3.97 1.7 21200 9940 2.13

16 2-methyl- 0.96 41.0 32200 16100 2.00 2-buten-l-ol

17 - 1.91 20.4 30600 15400 1.99

18 • 2.97 12.6 29900 15300 1.95

19 3.83 9.6 30300 15500 1.95

20 5.74 3.2 31400 15900 1.97

Table 3 Catalyst l,2-ethylene-bis(indenyl) hafnium dichloride

Example Monomer Monomer Yield M„ M n MJM„ amount g mmol

21 5-hexenol 0.50 3.4 71100 34700 2.05

22 1.00 0.6 42600 20500 2.08

23 » 1.50 0.5 36700 18300 2.01

24 2-methyl- 1.00 10.5 94300 45700 2.06 2-buten-l-ol

25 - 2.01 5.6 91700 44000 2.08

26 - 3.01 3.7 86000 40200 2.14

27 4.02 1.1 73600 33700 2.18

28 5.02 0.2 51700 23600 2.19