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
  • C08F210/04—Monomers containing three or four carbon atoms
  • C08F210/06—Propene
• • 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
  • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
  • C08F212/02—Monomers containing only one unsaturated aliphatic radical
  • C08F212/04—Monomers containing only one unsaturated aliphatic radical containing one ring
  • C08F212/06—Hydrocarbons
  • C08F212/08—Styrene
• • 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
• • 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
  • C08F212/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
• • 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
  • C08F2420/00—Metallocene catalysts
  • C08F2420/02—Cp or analog bridged to a non-Cp X anionic donor

Definitions

• the present invention relates to a process for the production of a copolymer, in particular a copolymer comprising styrene units and propylene units.
• the copolymer produced according to the present method is generally a random copolymer which is crystalline and easily processible.
• Metallocene catalysts are known to be useful in various polymerisation processes. For example, in EP 0581236, specific metallocene catalysts are described as being useful for the production of isotactic polypropylene (iPP).
• the present invention provides a method for the production of a copolymer of styrene and propylene, which method comprises copolymerising styrene and propylene in the presence of a metallocene catalyst, wherein the metallocene catalyst comprises a metallocene having either formula (I): R"(CpR m )(FluR'n)MQ2 (I)
• Cp comprises a cyclo pentad ienyl ring
• Flu comprises a fluorenyl ring
• R" comprises a structural bridge imparting stereorigidity to the component
• each R is the same or different and is an organic group
• m is an integer of from 0-4
• each R' is the same or different and is an organic group
• n is an integer of from 0-8
• M is a metal atom from group 4 of the Periodic Table or is vanadium
• each Q is a hydrocarbon having from 1 -20 carbon atoms or is a halogen
• copolymerisation means polymerising two or more olefin monomers, one of which being a styrene monomer, together in the same reaction zone under polymerisation conditions. It is preferred that the present method involves the copolymerisation of styrene with propylene to form a propylene-styrene copolymer. However, two, three or more further olefin monomers may be polymerised together with styrene in the present methods, if desired, to form, for example, a terpolymer.
• the methods of the present invention are particularly advantageous, since they allow for the production of improved styrene-propylene copolymers, especially random copolymers, having good processibility, and high crystallinity and good optical properties, such as low haze and high transparency.
• the catalysts used in the present invention have no meso form (they are single site catalysts) and do not suffer the problems of producing extractables, or low molecular weight product.
• the substituents that may be present on the cyclopentadiene and fluorene rings will now be described in more detail.
• the substituent or substituents are not particularly limited.
• the cyclopentadiene ring (Cp) may be unsubstituted, but is preferably at least mono-substituted. If desired, it may comprise one or more further substituents, provided that these further substituents do not adversely interfere with the ability of the present method to produce random olefin copolymers.
• the Cp ring may be substituted with the same substituent throughout, or with different substituents.
• the fluorene ring (Flu) may be substituted or unsubstituted and may also be substituted with the same substituent throughout, or with different substituents. Most preferably it is symmetrically substituted.
• the substituents on the Cp and Flu rings are not particularly limited and may comprise any organic group and/or one or more atoms from any of groups 13, 14, 15, 16, 17 of the Periodic Table, such as a B, Si, C, N, P, O, or S atom or a halogen atom (e.g. F, CI, Br or I).
• the organic group preferably comprises a hydrocarbon group.
• the hydrocarbon group may comprise a straight chain, a branched chain or a cyclic group. Independently, the hydrocarbon group may comprise an aliphatic or an aromatic group. Also independently, the hydrocarbon group may comprise a saturated or unsaturated group. When the hydrocarbon comprises an unsaturated group, it may comprise one or more alkene functionalities and/or one or more alkyne functionalities. When the hydrocarbon comprises a straight or branched chain group, it may comprise one or more primary, secondary and/or tertiary alkyl groups.
• the hydrocarbon comprises a cyclic group it may comprise an aromatic ring, an aliphatic ring, a heterocyclic group, and/or fused ring derivatives of these groups.
• the cyclic group may thus comprise a benzene, naphthalene, anthracene, indene, fluorene, pyridine, quinoline, thiophene, benzothiophene, furan, benzofuran, pyrrole, indole, imidazole, thiazole, and/or an oxazole group, as well as regioisomers of the above groups.
• the number of carbon atoms in the hydrocarbon group is not especially limited, but preferably the hydrocarbon group comprises from 1-40 C atoms.
• the hydrocarbon group may thus be a lower hydrocarbon (1-6 C atoms) or a higher hydrocarbon (7 C atoms or more, e.g. 7-40 C atoms).
• the number of atoms in the ring of the cyclic group is not especially limited, but preferably the ring of the cyclic group comprises from 3-10 atoms, such as 3, 4, 5, 6 or 7 atoms.
• the groups comprising heteroatoms described above, as well as any of the other groups defined above, may comprise one or more heteroatoms from any of groups 13, 14, 15, 16, 17 of the Periodic Table, such as a B, C, Si, N, P, O, or S atom or a halogen atom (e.g. F, CI, Br or I).
• the substituent may comprise one or more of any of the common functional groups in organic chemistry, such as hydroxy groups, carboxylic acid groups, ester groups, ether groups, aldehyde groups, ketone groups, amine groups, amide groups, imine groups, thiol groups, thioether groups, sulphate groups, sulphonic acid groups, and phosphate groups etc.
• the substituent may also comprise derivatives of these groups, such as carboxylic acid anhydrydes and carboxylic acid halides.
• any substituent may comprise a combination of two or more of the substituents and/or functional groups defined above.
• the substituents are independently selected from an aryl group and a hydrocarbyl group having from 1-20 carbon atoms.
• the most preferred substituents are methyl groups or butyl groups.
• Other preferred substituents include Et, n-Pr, i-Pr, n-Bu, t-Bu, M ⁇ 3Si, R-O, cycloalkyl, and halogen.
• At least one group R comprises a bulky group of the formula ZR*3 in which Z is an atom from group 14 of the Periodic Table and each R* is the same or different and is chosen from a hydrogen or a hydrocarbyl group having from 1-20 carbon atoms.
• at least one further group R is present comprising a group of the formula YR#3 in which Y is an atom from group 14 of the Periodic Table, and each R# is the same or different and is chosen from a hydrogen or a hydrocarbyl group having from 1 -7 carbon atoms.
• At least one group R is positioned on the cyclopentadienyl ring such that it is distal to the bridge R". However, in some embodiments of the invention at least one group R is positioned on the cyclopentadienyl ring such that it is proximal to the bridge R".
• the cyclopentadienyl ring comprises a bulky substituent ZR*3 distal to the bridge R" and a substituent YR#3 proximal to the bridge and non-vicinal to ZR * 3-
• the cyclopentadienyl ring comprises a substituent ZR*3 distal to the bridge R"; a substituent YR#3 proximal to the bridge R" and non-vicinal to ZR * 3; and a further substituent YR#3 proximal to the bridge and vicinal to ZR*3.
• the cyclopentadienyl ring may also comprise two substituents ZR * 3, each distal to the bridge R", if desired.
• Z and Y in the above formulae independently comprise carbon or silicon.
• the catalyst compounds used in the present methods are typically compounds in which ZR*3 is selected from C(CH3)3, C(CH3)2Ph, CPh3, and Si(CH3)3. It is particularly preferred that ZR*3 comprises (CH3)3.
• YR#3 comprises a methyl group or a trimethylsilyl group (TMS)
• the substitution pattern of the fluorene ring is not especially limited, provided that it does not adversely interfere with the copolymerisation method of the present invention.
• the fluorenyl ring is preferably symmetrically substituted. Most preferably both the 3- and the 6-position are substituted in catalysts of type (I), and of type (II).
• the fluorenyl ring comprises a substituent at the 2-position and at the 7-position.
• the group X is an atom from group 15 of the Periodic Table, particularly N or P.
• group 15 When X is from group 16 it will be apparent that X is not further substituted. However, when X is from group 15, it will be apparent that X will be further substituted to make up the required valence of the N or P atom. In this instance, further substitution may be any hydrocarbon group already discussed above. Most preferably however, the group is a bulky group, such as a tertiary butyl group.
• the catalysts of type (II) most preferably have the following structure:
• R1 and R2 are substituents at both the 2- and 7-positions, or both the 3- and 6-positions of the fluorenyl group, and are bulky groups of the formula ZR*3 in which Z is an atom from group 14 of the Periodic Table and each R* is the same or different and is chosen from a hydrogen or a hydrocarbyl group having from 1 -20 carbon atoms.
• R ⁇ and R ⁇ are both *Bu groups. It is particularly preferred that these *Bu 9 r oups are in the 3-position and the 6-position.
• R comprises an alkylidene group having 1 to 20 carbon atoms, a germanium group (e.g. a dialkyl germanium group), a silicon group (e.g. a dialkyl silicon group), a siloxane group (e.g. a dialkyl siloxane group), an alkyl phosphine group or an amine group.
• the substituent comprises a silyl radical or a hydrocarbyl radical having at least one carbon atom to form the bridge, such as a substituted or unsubstituted ethylenyl radical (e.g. - CH2CH2-).
• R" is isopropylidene (M ⁇ 2C), Ph2C, ethylenyl, or Me2Si.
• the metallocene compounds used in the present invention are those wherein M is Ti, Zr, or Hf.
• the Q groups attached to the metal atoms are alkyl groups having from 1 to 6 carbon atoms, preferably methyl groups.
• Q may be a halogen, such as CI.
• the further optional olefin employed in the present invention in addition to styrene and propylene is not particularly limited, and may be any olefin. Suitable olefins include ethylene, propylene, butene, pentene and hexene. Preferably the olefin is an alpha-olefin.
• the catalyst used in the present methods may comprise one or more activating agents capable of activating any one or more of the catalyst components. Typically, the activating agent comprises an aluminium- or boron-containing activating agent.
• Suitable aluminium-containing activating agents comprise an alumoxane, an alkyl aluminium compound and/or a Lewis acid.
• alumoxanes that can be used in the present invention are well known and preferably comprise oligomeric linear and/or cyclic alkyl alumoxanes represented by the formula (I):
• Suitable boron-containing activating agents may comprise a triphenylcarbenium boronate, such as tetrakis-pentafluorophenyl-borato-triphenylcarbenium as described in EP-A-0427696:
• activating agents include hydroxy isobutylaluminium and a metal aluminoxinate. These are particularly preferred when at least one Q in the general formula for metallocenes comprises an alkyl group.
• the catalyst systems employed in the present invention may be employed in any type of copolymerisation method, provided that the required catalytic activity is not impaired.
• the catalyst system is employed in a solution polymerisation process, which is homogeneous, or a slurry process, which is heterogeneous.
• typical solvents include hydrocarbons having 4-7 carbon atoms such as heptane, toluene or cyclohexane.
• a slurry process it is necessary to immobilise the catalyst system on an inert support, particularly a porous solid support such as talc, inorganic oxides and resinous support materials such as polyolefin.
• the support material is an inorganic oxide in its finely divided form.
• Suitable inorganic oxide materials that are desirably employed in accordance with this invention include group 2, 4, 13 or 14 metal oxides such as silica, alumina and mixtures thereof.
• Other inorganic oxides that may be employed, either alone or in combination with the silica or alumina, are magnesia, titania, zirconia, and the like.
• Other suitable support materials can be employed, for example, finely divided functionalised polyolefins such as finely divided polyethylene.
• the support is a silica support having a surface area of from 200- 700 m2/g and a pore volume of from 0.5-3 ml/g.
• the amount of activating agent and metallocene usefully employed in the preparation of the solid support catalyst can vary over a wide range.
• the activating agent to transition metal mole ratio is in the range between 1 :1 and 100:1 , preferably in the range 5:1 and 50:1.
• the order of addition of the catalyst components and activating agent to the support material can vary.
• activating agent dissolved in a suitable inert hydrocarbon solvent is added to the support material slurried in the same or other suitable hydrocarbon liquid and thereafter a mixture of the catalyst components is added to the slurry.
• Preferred solvents include mineral oils and the various hydrocarbons which are liquid at reaction temperature and which do not react with the individual ingredients.
• Illustrative examples of the useful solvents include the alkanes such as pentane, iso-pentane, hexane, heptane, octane and nonane; cycloalkanes such as cyclopentane and cyclohexane, and aromatics such as benzene, toluene, ethylbenzene and diethylbenzene.
• the support material is slurried in toluene and the catalyst components and activating agent are dissolved in toluene prior to addition to the support material.
• the present invention further provides use of a metallocene catalyst for producing a copolymer of styrene and propylene, wherein the metallocene catalyst comprises a metallocene having either formula (I):
• Cp comprises a cyclopentadienyl ring
• Flu comprises a fluorenyl ring
• R" comprises a structural bridge imparting stereorigidity to the component
• each R is the same or different and is an organic group
• m is an integer of from 0-4
• each R' is the same or different and is an organic group
• n is an integer of from 0-8
• M is a metal atom from group 4 of the Periodic Table or is vanadium
• each Q is a hydrocarbon having from 1 -20 carbon atoms or is a halogen
• the copolymer is preferably a styrene-propylene copolymer in which there is reasonably even distribution of the styrene and propylene units throughout each polymer molecule so that large blocks of each monomer unit do not form. Without being bound by theory, it is thought that this provides the polymer with its advantageous crystallinity, optical properties and processibility.
• the copolymers obtained according to the present invention have a styrene content of from 2 to 50 wt %, preferably of from 5 to 25 wt%.
• Figure 1 represents the 1 H NMR spectra of complex Bua-CisHe-Si ⁇ ea- N'ButyTiCk in benzene-d ⁇ at a temperature of 20 °C and at 200 MHz.
• Figure 1 represents the 1 H NMR spectra of complex N t Bu ⁇ Ti_Hle 2 in benzene-d6 at a temperature of 20 °C and at 200 MHz.
• Figure 3 represents the molecular structure of complex ⁇ t Bu 2 -C ⁇ 3 H 6 -SiMe2- N'Bi ⁇ TiM ⁇ z.
• Figure 4 represents the 13 C ⁇ 1 H ⁇ NMR spectrum of the propylene-styrene copolymer in CDCI 3 at a temperature of 60 °C.
• the new corresponding dialkyl complex ⁇ 3,6- t Bu2C ⁇ 3 H6SiMe 2 N t Bu ⁇ TiMe2 (2) was obtained as follows. 170 mg (0.339 mmol) of complex (1) in 30 mL of toluene at a temperature of -40 °C were added under vigorous stirring to 2 equivalents of MeLi (0.38 mL of a 1.6 M solution in Et 2 O, or 0.677 mmol). The reaction mixture was allowed to warm to room temperature and then stirred for 12 h. The brown- orange solution was decanted from precipitate and volatiles were removed in vacuum to give 0.15 g of complex 2 as an orange solid with a yield of 91%. Orange-yellow crystals of complex 2 suitable for X-ray analysis were grown from a pentane solution.
• a glass high-pressure reactor was charged with 50 mL of freshly distilled solvent under argon flash.
• the reactor was loaded with styrene and propylene as described in Table I, at atmospheric pressure and a solution of catalyst in 5 mL of toluene was injected by syringe.
• Mechanic stirring at 1,000 rpm was started and the required pressure of gas (typically 5 atm) was maintained constant.
• the reaction was quenched by adding 2 mL of a 10 % solution of HCI in methanol.
• the polymer formed was precipitated by adding of 300 mL of methanol. The precipitate was then washed and dried in vacuum.
• the polymerisation conditions and results are displayed in Table I.
• the copolymers according to the present invention have only a minor fraction that is soluble in CHCI 3 and tetrahydrofuran (THF) at room temperature. Both the soluble fraction at room temperature in CDCI 3 and the whole sample soluble at 130 °C in C 6 H CI 2 show a low incorporation percentage of styrene of 4 to 5 mol% as determined by NMR. They have a low molecular weight and a narrow polydispersity. The polydispersity is defined as the ratio Mw/Mn of the weight average molecular weight Mw to the number average molecular weight Mn. The molecular weights were determined by Gel Permeation Chromatography (GPC).
• the polymers recovered had poor solubility in CDCI 3 and THF at room temperature and they were largely soluble (about 80 %) in hot CHCI 3 .
• the fraction that was not soluble in CHCI 3 was a mixture of syndiotactic polystyrene (sPS) and of syndiotactic polypropylene (sPP) as determined by DSC.
• the soluble fraction was analysed by GPC: it revealed a low molecular weight and a narrow polydispersity.
• the styrene content as determined by 1 H NMR spectroscopy gave a styrene content of about 18 mol%. Increasing the styrene content led to polymer products also composed of homopolymers of sPS and sPP.

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