Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
  • C08F210/18—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers with non-conjugated dienes, e.g. EPT rubbers

Definitions

• the invention is related to an elastomer formed by the copolymer of ethylene and propylene, and further, to a manufacturing method thereof by means of a metallocene compound and an alumoxane catalyst.
• Copolymers with elastomeric, that is, rubberlike elasticity characteristics have been o manufactured from ethylene and propylene.
• An important characterizing property of elastomers is their rubberlike behavior, and particularly, as wide as possible operating range of such a property, or alternatively, a controlled and desired change of the elastic properties with variations in the operating 5 ' conditions and also in the raw materials of the elastomer, that is, the monomers.
• the desired goal can be attained by controlling the properties of the basic component, the elastomer, which can be imple ⁇ mented by altering, in addition to the reaction conditions (temperature, pressure, media, reactor type, etc.), particularly the catalyst utilized in the polymerization 0 process.
• a copolymer can be produced by means of different catalyst systems, e.g., ethylene and propylene have been copolymerized into an elastomeric product utilizing a catalyst system formed by a procatalyst composition comprising a compound of a transition 5 metal of the IN-NI subgroup of the Periodic Table of Elements, particularly titanium, zirconium and/or vanadium, and a cocatalyst formed by an organic compound of a metal of the I— III major group of the Periodic Table of Elements, particularly an organic aluminium compound.
• Several other catalyst system components e.g., electron donor compounds, and other additives required in polymerization reactions such as 0 different kinds of media can be utilized.
• the reaction met : urn can be a compound which will be incorporated in the product in its entirety or )art, or alternatively, a molecular- weight controlling compound (chain transfer agent).
• chain transfer agent Suited for controlling the molecular weight and its distribution only, hydrogen is a chain transfer agent which 5 can be introduced to the polymerization reaction with the significant benefit of not bringing along any unwanted atoms to the produced polymer.
• a great number of other additives may be employed to the end of improving different properties of the product.
• An essential component of the procatalyst composition may be a compound of a transi ⁇ tion metal, termed as metallocene, in which the metal has aromatic rings joined to it, typically hydrocarbons which can further be substituted, as well as halogen groups. 0
• the substituent may also contain heteroatoms.
• the halogen group joining to the metal typically is a simple halogen atom, advantageously chlorine, and the number of halogen atoms is two if the transition metal has a valence state of 4.
• the transition metal is titanium or zirconium, and the aromatic ring is five-membered and two rings join to one metal atom.
• said rings are bis-pentadienyl or bis-indenyl 5 derivatives, which can be substituted as mentioned above.
• the cocatalyst used with such a procatalyst is an alumoxane compound in which two or a greater number of aluminium atoms join via the oxygen atom to each other, and the aluminium atoms can further have a variety of substituents which typically are hydrocarbon groups, advantageously alkyl groups.
• the copolymer is principally produced from ethylene and propylene, while additionally multi-unsaturated compounds can be used, chiefly polyene hydrocarbons, particularly diolefins. Then, unsaturated bonds remain within the polymer chain that can be useful with a greater or lesser reactivity when other chemical groups are desiredly joined to the polymer by a chemical bond or when the polymer is desiredly bridged or vulcan ⁇ ized, the latter being a traditionally typical process for treating rubber to the end of achieving a structure most suited to different applications.
• the proportion of the polyenes is small, e.g., 0.5 - 2 mol-% .
• the proportion of ethylene units in the elastomeric ethylene-propylene copolymer is relatively high, however, rarely in excess of 80 %, and even more rarely in excess of 95 % .
• the molecular weight of the copolymer is typically rather low, not greater than a few thousands with a theoretical maximum at approx. 10 000 g/mol if the elastomeric properties of the copolymer are desiredly retained.
• Patent application EP 223,394 discloses the production of an elastomeric ethylene- propylene copolymer having a low molecular weight (number-average molecular weight in the range 1800 - 4400 g/mol) using a catalyst system formed by bis-cyclopenta- dienyl-Zr-dichloride and methylalumoxane.
• the intrinsic viscosity of such a polymer is 0.025 - 0.6 dl/g determined in tetraline at 135 °C.
• the ethylene content in the product is 20 - 80 % , according to the examples 54-69 % .
• Patent application EP 273,654 is related to an unsaturated copolymer made from ethylene and nonconjugated diene; also propylene being proposed as a possible comonomer, while no experimental proof is given.
• the catalyst system used is a com ⁇ position formed by bis-cyclopentadienyl-Zr-dichloride and methylalumoxane.
• the ethylene content of the product is high, in the range 96 - 99 %, and the rest is essentially at least a diene.
• the molecular weight range of the product is disclosed in a broad manner: not less than 500, advantageously in excess of 10 000 and even up to 2 000 000 g/mol, and according to the examples in the range 60 000 - 120 000 g/mol.
• the viscosity values of the product are not given.
• the intrinsic viscosity is over 0.8 dl/g in decaline at 135 °C when the ethylene content of the copolymer is approx. 65 wt-%.
• the limiting viscosity number is determined using an apparatus comprising, e.g. , a Lauda UD15 heating bath and Schott timer, using the Ubbelohde capillary.
• the sample from which the limiting viscosity number was determined weighed 30 mg and it was dissolved in 50 ml decaline at 135 °C, and the limiting viscosity number computed on the basis of one measurement point as proposed by Solomon, O.F., Ciuta, I.Z., J. Appl. Polvm. Sci. 6(1962), p. 683.
• Mooney viscosity MV characterizes the processability of the product and it is determined from a polymer melt.
• the glass transition point and the loss factor which correlate with the low- temperature properties such as the low-temperature impact strength, can be determined by thermal analysis methods such as DTMA.
• DTMA thermal analysis methods
• the ethylene content of the product is high, in excess of 65 wt-%, advantageously 80 - 90 wt-% .
• the product is elastomeric and the different monomers are homogeneously distributed over the molecule chain, that is, blocks consisting of ethylene alone have not been formed and then mixed with copolymer blocks.
• This homogeneity can be seen from, e.g., the Random Index (RI) value which characterizes the proportion of monomer units not incorporated in homopolymer blocks comprising at least three identical monomer units.
• the index is computed from triad distributions obtained from the C 13 NMR spectrum:
• E and P are ethylene and propylene monomer units
• PPE, EPE, etc. denote the molar proportions of the triads in the polymer product.
• this distribution of comonomer units is clearly more inhomogeneous indicating that the number of homopolymer blocks is greater, which is evidenced by the RI values given in the tables of comparative examples.
• the copolymer made by a slurry process whereby the medium can be either a liquid polymer, namely propylene, or a hydrocarbon solvent, advantageously aliphatic paraffin such as hexane, heptane, etc.
• the polymerization temperature herein is rather low, typically less than 50 °C, advantageously 0 - 30 °C.
• Gas phase polymerization can also be used, whereby a desired amount of propylene, and optionally also a diene, is mixed with gaseous ethylene in, e.g., a fluid-bed reactor in liquid droplet form, because a relatively low temperature must be used also herein.
• the catalyst used is a compound of bis-cycloalkadiene and a transition metal.
• the tran ⁇ sition metal is advantageously titanium or zirconium.
• the cycloalkadiene is advanta ⁇ geously 5-membered, that is, cyclopentadiene which can be substituted with a hydro ⁇ carbon group such as an alkyl group, that is, a methyl-, ethyl-, propyl-, etc. -cyclo- pentadiene, or alternatively, with a hydrocarbon group containing also a heteroatom such as, e.g., a silyl or silanylene group.
• the cycloalkadiene can also be indene.
• the cocatalyst used is an alumoxane compound.
• Methylalumoxane has been found suitable, while also other, more complex alumoxane compounds can be used of which alkylalumoxanes and their polymerized compounds deserve mentioning.
• a metallocene compound and alumoxane were used to produce the catalyst in amounts having the mole ratio of aluminium-to-zirconium in the range 1500 - 5000, advantageously 3000 -4200.
• Example 1 6.9 mg bis-cyclopentadienyl-Zr-dichloride catalyst was weighed into a flask in a nitro ⁇ gen chamber having an oxygen content of less than 15 ppm and dissolved in toluene. The solution was transferred from the flask to a metal funnel into which 4200 mg methylalumoxane (MAO) was transferred after storage for approx. half a year in a nitrogen atmosphere cabinet, said alumoxane being a 30 wt-% toluene solution by Schering AG, whereby the Al-to-Zr mole ratio became 3000. The funnel was installed permanently onto a 2 1 polymerization reactor.
• MAO methylalumoxane
• the reactor was vacuumed prior to purging with nitrogen, and it was equipped with an anchor-shaped agitator.
• the reactor was cooled to -5.0 °C and 430 g liquid propylene was introduced to the vacuumed reactor.
• the reactor temperature was next raised to 15 °C and the catalyst system in which the catalyst and the cocatalyst had been contacted for 7 min with each other was flushed with compressed nitrogen gas from the funnel to the reactor.
• Ethylene was introduced to the reactor under 10.7 bar (gauge) pressure.
• the rotation speed of the agitator was consistently 500 r/min.
• the reactor temperature was adjusted by rotating water-ethanol mixture in the heat jacket of the reactor, while the reactor pressure was controlled automatically by a solenoid valve. After 30 min of reaction, the unreacted propylene was evaporated away and 74 g of the product, that is, ethylene-propylene copolymer was obtained.
• the product properties are given in Table 1.
• Example 2 The polymerization was carried out as in Example 1 except that 6.0 mg catalyst was used and 460 g propylene was introduced to the reactor. The absolute pressure in the reactor was now 11.1 bar. 58 g the product was obtained. The product properties are given in Table 1.
• Example 3 The polymerization was carried out as in Example 1 except that 7.9 mg catalyst was used and 470 g propylene was introduced to the reactor. The absolute pressure in the reactor was now 11.4 bar. 50 g the product was obtained. The product properties are given in Table 1.
• Example 1 The polymerization was carried out as in Example 1 except that 6.4 mg catalyst was used, and 5600 mg cocatalyst was added, whereby the Al-to-Zr mole ratio was 4200.
• the absolute pressure in the reactor was now 11.4 bar. 49 g the product was obtained.
• the product properties are given in Table 1.
• Example 1 The polymerization was carried out as in Example 1 except that 3.0 mg catalyst was used, and 1400 mg cocatalyst (as 10 wt-% MAO solution) was added, whereby the Al-to-Zr mole ratio was 3300. 350 g propylene was added to the reactor. The absolute pressure in the reactor, whose volume in this example was 1 1, was 15.0 bar. 32 g the product was obtained. The product properties are given in Table 1.
• the polymerization was carried out as in Example 1 except that the reactor volume was 0.5 1 and 200 g propylene was introduced into it. 1 mg catalyst was used, and 290 mg cocatalyst (as 10 wt-% MAO solution) was added, whereby the Al-to-Zr mole ratio was 2000. The temperature in the reactor was 29 °C and the absolute pressure was 18.9 bar. 10 g the product was obtained after processing for 25 min. The product properties are given in Table 1.
• Example 7 The polymerization was carried out as in Example 1 except that the reactor volume was 1 1 and 350 g propylene was introduced into it. 3 mg catalyst was used, and 1400 mg cocatalyst (as 10 wt-% MAO solution) was added, whereby the Al-to-Zr mole ratio was 2000. The temperature in the reactor was 14 °C and the absolute pressure was 19.0 bar. 10 g the product was obtained after processing for 20 min. The product properties are given in Table 1.
• a 0.5 1 polymerization reactor equipped with a propeller agitator was vacuumed and purged with nitrogen. Then, 207 g heptane was introduced to the reactor and 220 mg
• MAO solution (as 10 wt-% toluene solution by Schering AG, stored approx. half a year in nitrogen atmosphere cabinet) was added to the reactor, and the monomer mixture feed to the reactor was turned on.
• the ethylene flow rate was 2.0 1/min and the propylene flow rate was 0.2 1/min (gas flow rates are given referenced to NTP); the flow was maintained constant during the entire polymerization process in accordance with the so-called semi-flow method.
• the temperature in the reactor was 50 °C and the absolute pressure
• the reactor pressure was controlled by a solenoid valve and the temperature was adjusted by circulating thermostatted water in the heat jacket of the reactor.
• the agitator rotational speed was 800 r/min.
• the polymerization time was 10 min, after which 8.8 g the product was obtained.
• the product properties are given in Table 1.
• Example 9 The polymerization was carried out as in Example 8 except that the propylene flow rate was 0.05 1/min. The product yield was 7.9 g. The product properties are given in Table 1.
• Example 10 The polymerization was carried out as in Example 8 except that the propylene flow rate was 0.4 1/min. The product yield was 9.7 g. The product properties are given in Table 1. To obtain comparative results, a series of reactions were carried out to copolymerize ethylene and propylene into an elastomeric product using both a titanium- and a vanadium-based catalyst system. A similar polymerization procedure and apparatus as in the above examples was used, with the exception that hydrogen acting as a chain transfer agent was added to the reactant mixture during polymerization, which step was not included in the reaction carried out using the catalyst system according to the invention.
• the titanium catalyst system comprised TiCl 4 procatalyst on MgCl 2 support and of triethylaluminium cocatalyst, in which system the Al-to-Ti mole ratio was 200 and the titanium content was 7.2 wt-% .
• the vanadium catalyst system comprised NOCl 3 and diethylaluminiumchloride (DEAC), in which system the V-to-Cl mole ratio was 4200.

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• Chemical & Material Sciences (AREA)
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• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

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Cited By (3)

Citations (3)

• 1993
  • 1993-03-18 FI FI931194A patent/FI95582C/sv not_active IP Right Cessation
• 1994
  • 1994-03-08 JP JP6520681A patent/JPH08508057A/ja active Pending
  • 1994-03-08 CA CA 2158464 patent/CA2158464A1/en not_active Abandoned
  • 1994-03-08 WO PCT/FI1994/000081 patent/WO1994021692A1/en not_active Application Discontinuation
  • 1994-03-08 EP EP94909130A patent/EP0689554A1/en not_active Withdrawn
• 1995
  • 1995-09-18 NO NO953674A patent/NO953674L/no unknown

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