FI95582B - Ethylene propylene copolymer and its production method - Google Patents

Description

95582

The invention relates to an elastomer of ethylene and propylene and optionally of diolefin copolymer 5 and to a process for its preparation by means of a catalyst formed by bis-cyclopentadienyl-Zr dichloride and alumoxane.

Copolymers with elastomeric, i.e. rubbery, properties have been made from ethylene and propylene.

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An important property of elastomers is their rubberiness and its retention over the widest possible range of operating conditions or the controlled and desired change in elastic properties as conditions and also the monomers of the polymer raw materials change. Not only by varying the additives, this can also be achieved by adjusting the properties of the basic component itself, i.e. the polymer 15, which is possible not only by changing the reaction conditions (temperature, pressure, media, reactor type, etc.) but above all by varying the catalyst used in the preparation.

The copolymer can be prepared by various catalyst compositions, e.g. -with ethylene and propylene into an elastomeric product. Numerous other catalyst components, for example electron donating compounds, and other additives required in connection with the polymerization, such as media, can be used.

The medium can be not only a monomer (so-called bulk polymerization) but also a compound which remains in whole or in part in the product or, for example, a molecular weight regulator (so-called chain transfer agent).

30 The chain transfer agent added during polymerization, which merely controls the molecular weight and its distribution, is hydrogen, which has the significant advantage that no foreign atoms enter the resulting polymer. It is possible to use a large number of other additives aimed at improving various product properties.

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Although it is common to use a roughly two-component catalyst composition in the preparation of an ethylene-propylene elastomer, in practice there are very many components today and the composition is prepared by very different methods, which can be very multi-step and complicated. Typical so-called Ziegler-Natta catalyst compositions are disclosed in U.S. Pat. No. 3,789,036 and DE 2,505,825.

The so-called transition metal can also be used as an essential component of the procatalyst composition. a metallocene compound having aromatic rings attached to the metal, usually hydrocarbons which may be substituted, and halogen groups. The substituent may also contain heteroatoms. the halogen group is usually a halogen atom only, preferably chlorine, and there are two of them if the transition metal is 4-membered. Generally, the transition metal is titanium or zirconium, and the aromatic ring is five-membered and the rings are attached to one metal atom in two pieces. These are most often bis-pentadienyl or bis-15 indenyl derivatives, which can thus be substituted. As the cocatalyst with such a procatalyst, an alumoxane compound is used in which two or more aluminum atoms are connected to each other via an oxygen atom and the aluminum atoms may additionally have various substituents, but usually hydrocarbon groups, preferably alkyl groups.

The copolymer is mainly made of ethylene and propylene, but polyunsaturated compounds, mainly polyene hydrocarbons, especially diolefins, are often used in addition. In this case, unsaturated bonds remain in the middle of the polymer chain, which are more or less reactive if necessary to attach other groups to the polymer by chemical bonding or to crosslink or vulcanize the polymer, which is traditionally a typical treatment for rubber to provide a suitable structure for applications. Usually the proportion of polyenes is small, for example 0.5 to 2 mol%.

In general, the proportion of ethylene units in an elastomeric ethylene-propylene copolymer is relatively high, but less frequently exceeds 80% and even less frequently exceeds 95%. The molecular weight of the copolymer is usually quite low, up to a few thousand, and the upper limit may be about 10,000 g / mol if the copolymer is to be elastomeric.

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Patent application EP 223 394 discloses the preparation of an elastomeric ethylene-propylene copolymer having a low molecular weight (number average molecular weight 1800-4400 g / mol) by means of a catalyst-5 complex of bis-cyclopentadienyl-Zr-dichloride and methylalumoxane. g determined in tetralin at 135 [deg.] C. The product has an ethylene content of 20-80%, 54-69% according to the examples.

Patent application EP 273 654 relates to an unsaturated copolymer made from ethylene and a non-conjugated diene, but propylene is also disclosed as a possible comonomer, although there is no experimental evidence. The catalyst used is a composition of bis-pentacyclodylyl-Zr-dichloride and methylalumoxane. The ethylene content of the product is high, 96-99%, and the remainder is essentially at least diene. The molecular weight range of the product is stated very broadly: more than 500, most preferably more than 10,000 up to 2,000,000 g / mol and according to the examples 60,000 to 120,000 g / mol have been obtained. Product viscosity values are not reported.

It has now surprisingly been found that a catalyst complex of bicyclopentadienyl-zirconium dichloride and methyl laloxane can polymerize a copolymer of ethylene and propylene and possibly a diolefin which is elastomeric, highly flowable and highly soluble in the melt state and due to its low viscosity then a swellable product with a high molecular weight. The weight average molecular weight is 10,000 to 250,000 g / mol, preferably 40,000 to 90,000 g / mol. The molecular weight distribution of the product MWD = Μ * / Μ „is narrow, preferably only about 2.0 25 to 2.5. The intrinsic viscosity is greater than 0.8 dl / g in decalin at 135 ° C when the copolymer has an ethylene content of about 65% by weight. The intrinsic viscosity is determined, for example, with a device containing a Laud UD15 bath and a Schott clock device using an Ubbelohde capillary. The sample from which the intrinsic viscosity was determined was 30 mg and was dissolved in 135. At 50 ° C to 50 ml of decalin, and the intrinsic viscosity was calculated on the basis of a single point, as reported by Solomon, O.F., Ciuta, I.Z., J.Appl.Polym.Sci. 6 (1962) 683.

Important variables describing the quality of the product are also the Mooney viscosity MV, the glass transition point Tg and the loss factor tanS ^. MV describes the processability of the product and is determined from the polymer melt. Glass transition point and loss factor that correlate with cold properties 4,95582 mouths, e.g. impact resistance in the cold can be determined, for example, by thermal analysis such as DTMA. It can be seen from the examples and comparative examples that with the elastomers according to the invention these values are of the same order of magnitude, i.e. the product is qualitatively comparable in this respect to the elastomers obtained with other types of catalyst systems.

The ethylene content of the product is thus high, more than 65% by weight up to 95% by weight, preferably 80-90% by weight. Nevertheless, the product is elastomeric and the various monomers are evenly distributed throughout the molecular chain, i.e. no ethylene-only blocks are formed when mixed with the copolymer blocks. This regularity can be seen, for example, in the so-called A Random Index (R.I) that describes how much of the monomer units are not in homopolymer blocks containing at least three of the same monomer units. It is calculated from the 3C NMR spectrum on the basis of triad distributions: 15 (PPE + EPE + PEP + EEP) / (PPP + PPE + EPE -I- PEP + EEP + EEE) where E and P are ethylene and propylene monomer units and PPE, EPE etc. triads •: molar proportions in the product polymer. In elastomers prepared with titanium and vanadium-based catalysts, this distribution of comonomer units is clearly more irregular, i.e. more homopolymer blocks are present, which can be seen from the R.I. values of the product given in the comparative examples.

The copolymer is prepared by a slurry process in which the medium may be either a liquid monomer, i.e. propylene, or a hydrocarbon solvent, preferably an aliphatic paraffin such as hexane, heptane, etc. In this case, the polymerization temperature is quite low, generally below 50 ° C, preferably 0-30 ° C. Gas phase polymerization can also be used, in which case the desired amount of propylene and possibly diene is mixed with gaseous ethylene, for example in a fluidized bed reactor, as liquid droplets, since a relatively low temperature must still be used.

The bis-cycloalkadiene transition metal compound is used as the catalyst. The transition metal is preferably titanium or zirconium. The cycloalkadiene is preferably a 5-membered or cyclopentadiene which may be substituted by a hydrocarbon group, for example an alkyl group, i.e. 5,95582 methyl, ethyl, propyl, etc. cyclopentadiene, or also by a heteroatom-containing hydrocarbon group, for example a silyl or silanylene group. The cycloalkadiene may also be an indene.

5 The alumoxane compound is used as the cocatalyst. Methyl alumoxane has been found to be suitable, but other more complex alumoxane compounds are suitable, such as other alkyl alumoxanes and their polymerized compounds.

The metallocene compound and alumoxane were used in the preparation of the catalyst in such amounts that the molar ratio of aluminum to zirconium becomes 1500 to 5000, preferably 3000 to 4200.

The following are examples of the application of the catalyst according to the invention and, for comparison, examples of ethylene propylene elastomers obtained with previously known Ti and V-based catalyst systems.

Example 1.

6.9 mg of bis-cyclopentadienyl-Zr dichloride catalyst was weighed into a flask in a nitrogen cabinet having an oxygen content of less than 15 ppm and dissolved in toluene. The solution was transferred from the flask to 20 metal funnels to which was added 4200 mg of methylalumoxane (MAO) stored in a nitrogen cabinet for about six months in a 30 wt% toluene solution of Schering Ag to give an AL / Zr molar ratio of 3000. The funnel was set at 21 fixed to the polymerization reactor.

• The reactor was evacuated and nitrogenated and equipped with an anchor stirrer. The reactor was cooled to -5.0 ° C and 430 g of liquid propylene was introduced into the evacuated reactor. The reactor temperature was then raised to 15 ° C, and the catalyst mixture, in which the catalyst and cocatalyst had been in contact with each other for 7 minutes, was blown from the funnel into the reactor by means of an excess pressure of nitrogen. Ethylene was introduced into the reactor at an overpressure of 10.7 bar. The stirrer speed was 500 rpm at all times. The reactor temperature was controlled by circulating the water-ethanol mixture in the reactor jacket and the reactor pressure was automatically controlled by a solenoid valve. After 30 minutes, the unreacted propylene was evaporated to give 74 g of product, i.e. ethylene propylene copolymer. Product features are shown in Table 1.

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Example 2

The procedure was as in Example 1, but 6.0 mg of catalyst was used and 460 g of propylene were introduced into the reactor. The total reactor pressure was now 11.1 bar. 58 g of product were obtained. The characteristics of the product are shown in Table 1.

5

Example 3

The procedure was as in Example 1, but 7.9 mg of catalyst was used and 470 g of propylene were introduced into the reactor. The total reactor pressure was 11.4 bar. 50 g of product were obtained. The characteristics of the product are shown in Table 1.

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Example 4

The procedure was the same as in Example 1, but 6.4 mg of catalyst was used, 5600 mg of cocatalyst was added, giving an Al / Zr molar ratio of 4200. The total reactor pressure was 11.4 bar. 49 g of product were obtained. The characteristics of the product are shown in Table 1.

15

Example 5

The procedure was the same as in Example 1, but 3.0 mg of catalyst was used and 1400 mg of cocatalyst (10 wt% MAO solution) was added, giving an Al / Zr molar ratio of 3300. Propylene was introduced into the reactor at 350 g. The total pressure of the reactor, which was now 11 in size, was 15.0 to 20 bar. 32 g of product were obtained. The characteristics of the product are shown in Table 1.

Example 6

The procedure was as in Example 1, but the reactor was 0.5 L in size, and 200 g of propylene were introduced. 1 mg of catalyst and 290 mg of cocatalyst (10% w / w MAO solution) were used, with a molar ratio of Al / Zr of 2000. The reactor temperature was 29 ° C and the total pressure was 18.9 bar. 10 g of product were obtained in 25 minutes. The characteristics of the product are shown in Table 1.

Example 7 The procedure was as in Example 1, but the reactor was 1 L in size and 350 g of propylene were introduced. 3 mg of catalyst and 1400 mg of cocatalyst (10 wt% MAO solution) were used, with a molar ratio of Al / Zr of 2000. The reactor temperature was 14 ° C and the total pressure was 19.0 °. . U: t IIIH I IJ-M.

7 95582 bar. 10 g of product were obtained in 20 minutes. The characteristics of the product are shown in Table 1.

Example 8 (Comparative) A 0.5 L polymerization reactor equipped with a propeller stirrer was evacuated and nitrogenated. Then 207 g of heptane was introduced into the reactor, 220 mg of a MAO solution (10 wt% toluene solution, Schering Ag, stored for about half a year in a nitrogen cabinet) was added to the reactor, and the monomer mixture was fed to the reactor. The ethylene flow was 2.0 1 / min and the propylene flow was 0.2 1 / min (gas flows are reported in the so-called normal state): The flow was continued throughout the polymerization 10, i.e. the so-called a semi-flow method. After 5 minutes, 0.6 mg of bis-cyclopentadienyl-Zr dichloride was added to give an Al / Zr molar ratio of 2000. The reactor temperature was 50 ° C and the total pressure was 5.0 bar. The reactor pressure was controlled by a solenoid valve and the temperature by circulating water in the reactor jacket. The agitator speed was 800 rpm. The polymerization time was 10 minutes, during which 8.8 g of product 15 were obtained. The characteristics of the product are shown in Table 1.

Example 9 (comparison)

The procedure was as in Example 8, but the propylene flow was 0.05 l / min. The yield was 7.9 g. The characteristics of the product are shown in Table 1.

20

Example 10 (comparison)

The procedure was as in Example 8, but the propylene flow was 0.4 l / min. The yield was 9.7 g. The characteristics of the product are shown in Table 1.

For comparison, the copolymers of saqa ethylene and propylene into an elastomeric product were also made with both a titanium and vanadium-based catalyst system. A similar polymerization method and apparatus was used, with the exception of the addition of hydrogen to the reaction mixture during the polymerization as a chain transfer agent, which was not done using the catalyst system of the invention.

The titanium catalyst system consisted of a TiCl4 procatalyst supported on MgCl2 and a triethylaluminum cocatalyst with an Al / Ti molar ratio of 200 and a titanium content of 7.2 p- • · 95.982 8%. The vanadium catalyst system consisted of VOCl 3 and diethylaluminum chloride (DEAC) with a V / Cl molar ratio of 4200.

The results of the comparative experiments are shown in Table 2.

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Claims (5)

1. An elastic copolymer made of ethylene, propylene and optionally diolefin characterized in that it has been prepared by contacting in polymerizing conditions a monomer mixture containing ethylene, propylene and possibly diolefin present in a catalytic system containing bis-cyclopentadienyl-Zr -dichloride and alumoxane, to produce an elastic copolymer which dissolves in hydrocarbon solvents or swells thereof and which can be processed in molten form, whose average molar mass expressed in weight 10 is 10,000 - 250,000 g / mol, whose intrinsic viscosity is 0.8 - 4.0 dl / g measured in decalin at 135 ° C, the proportion of ethylene units being 65 - 95% by weight and having an even distribution of comonomer units. 2. A copolymer according to claim 1, characterized in that the copolymer having the ethylene moiety is 80-90% by weight. A copolymer according to claim 1 or 2, characterized in that the alumoxane is methylalumoxane. 20 4. Preparation to manufacture a copolymer according to claim 1, characterized in that ethylene with propylene and possibly diolefin may contact the catalytic system containing bis-cyclopentadienyl-Zr dichloride and alumoxane in suspension of liquid propylene or an aliphatic hydrocarbon or in gas phase at temperature 0 - 100 ° C, presumably 10 - 50 ° C, and the partial pressure of the ethylene is such that the ethylene unit proportion of the copolymer is 65 - 95% by weight. 25 Composition according to Claim 4, characterized in that alumoxane is methylalumoxane. il. itl.t Will III 4 Ml> · I