MXPA94007800A - Process for preparing dekylidine synodotactic aromatic polymers, metal reducal cationic utilizandocatalizers - Google Patents

Abstract

The present invention relates to a process for preparing syndiotactic polymers of vinylidene aromatic monomers, characterized in that it comprises contacting one or more aromatic vinylidene monomers, under polymerization conditions, with a catalytically effective amount of a catalyst comprising: 1) a metal complex corresponding to the formula: CpmMXnX'p wherein: Cp is a n5-substituted cyclopentadienyl or n5-substituted cyclopentadienyl group, M is a metal of group 4 or of the lanthanide series of the Periodic Table, Oxidation state +3; X, in each occurrence, is OR, where R is hydrocarbyl from 1 to 20 carbon atoms, X'is a neutral, inert donor ligand, myp are independently 0 or 1, n is an integer greater than or equal to 2, and the sum of m and n is 3; 2) a cation-forming activating cocatalyst, which comprises a non-coordinating, inert anion, and 3) an organometallic hydrocarbylation agent, the molar proportion of which is aromatic monovinylidene oxide: metal complex of 100: 1 to 1 x 1010: 1, and the molar ratio of hydrocarbylation agent being: metal complex of 2: 1 to 100

Description

"PROCESS FOR PREPARING AROM TICOS DE VINILIDENO STNDTOTACTTCOS USING CATIONIC METAL CATALYSTS REDUCED" INVE ?? TORBS s THOMAS H. H3SWHAN, KARBH. BOROD CHLíK * North American citizens * with dowiciilos at 2720 Georgetow Street, Midland »Michigan 48642» E.U.A »and 5S40 Carriage Lane» Ht. Plassassant, Michigan 48858 »E.0.A.

CAUSAHABIENTBs THE DOW CBEIIICAL COM AHY, a North American company, with address at 2030 Dow Center, Abbott Road »Midland * Michigan 48640, S.U.A.

SUMMARIZES A process for preparing syndiotectic vinylidene aromatic polymers, comprising contacting one or more vinylidene aromatic monomers with a catalyst comprising a group 4 cationic metal complex, wherein the metal is in the +3 oxidation state , formed from the corresponding complex containing metal-hydrocarbyloxy, in the presence of a hydrocarbylation agent.

DESCRIPTIVE MEMORY The present invention relates to a process for polymerizing aromatic vinylidene monomers, such as styrene, to produce polymers having a high degree of syndiotacticity, while controlling molecular weight. Said polymers can be used in the preparation of solid objects and articles, such as rollers, films, sheets and foamed objects, by means of molding, casting or the like. A process for preparing polymers of vinylidene aromatic monomers having a stereoregular structure with elevated syndiotacticity is described in US-A-4, 680, 353 by the use of metal coordination catalysts of group 4, in the state of oxidation + and an aluminoxane cocatalyst. US-A-5,066,741 discloses certain cationic metal compounds formed by reacting certain group 4 metal complex including +3 and +4 metal complexes, co-salts of ammonium or phosphonium of Bronsted acids, which contain an anion, compatible , not coordinator, with cationic oxidants that have a non-coordinating compatible anion. The complexes are usefully used as catalysts in the polymerization of vinylidene aromatic monomer polymers, which have a high stereoregular structure syndiotacticity.

In WO 93/19104, certain stabilized group 4 metal complexes are described, in which the metal is in the +3 oxidation state, and their use as addition polymerization catalysts. Finally, EP-A-493678 describes processes for preparing syndiotactic polystyrene using certain additional cationic metal compounds, formed by reacting group 4 metal alkoxides or similar complexes in the oxidation state +4, alkylating agents, cocatalyst activators, cation (including the ammonium or phosphonium salts of Bronsted acids cationic oxidizers containing a coordinated anion n). In accordance with the present invention, a novel process for preparing aromatic vinylidene monomer polymers having a high syndiotacticity group is now provided. The process comprises contacting at least one aromatic vinylidene monomer, polymerizable under polymerization conditions, with a catalyst comprising the combination of: (1) a metal complex of group 4 / hydrocarbyloxy, which corresponds to the formula: CpmMXnX'p where: Cp is a? -substituted cyclopentadienyl? -cyclopentadienyl group; M is a metal of group 4 or of the lanthanide series of the Periodic Table, in the oxidation state - * - 3 X, in each occurrence, is OR, wherein R and hydrocarbyl of 1 to 20 carbon atoms; X 'is a neutral, inert donor ligand; and p are independently 0 or 1; n is an integer greater than or equal to 2; and the sum of m and n is 3; (2) an activating cocatalyst, cation former, comprising a non-coordinating, inert anion; and (3) an organometallic hydrocarbylation agent. The present process allows the use of hydrocarbyloxy / metal complexes, especially alkoxide complexes that lack hydrocarbyl substituents. Such complexes are more soluble in common solvents used in the catalyst preparation, than their corresponding hydrocarbyl substituted derivatives, and can also be obtained more readily in commerce, than the metal complexes substituted with alkyl aryl. In addition, it has been found that the metal complexes in the +3 oxidation state obtain a significantly improved conversion of monomer and an increased efficiency in use, when compared to similar catalysts, based on complexes in oxidation state +4.

All references to the Periodic Table of the Elements hereof shall refer to the Periodic Table of the Elements published and recorded by CRC Press, Inc., 1989 In addition, by reference to a group or series reference shall be made to the group or series that is reflected in that Periodic Table of the Elements, using the IUPAC system to number the groups. As used herein, the term "syndiotechnic" refers to polymers having a stereoregular structure that is more than 50% syndiotactic of a racemic triad, as determined by nuclear magnetic resonance spectroscopy with carbon 13. Said polymers they can be usefully employed in the preparation of articles and objects (for example, by compression molding, injection molding or other suitable technique) having an extremely high resistance to deformation due to the effects of temperature. Illustrative, but not limiting, examples include alkoxide, aryloxide and arylalkoxide groups. Preferably, X independently at each occurrence is an alkoxy group of 1 to 4 carbon atoms, especially methoxy group. Illustrative, but not limiting examples of X include: ROR, RSR, NRs, PR3 and olefins or diolefins of 2 to 2 carbon atoms, wherein R is as previously defined. Said donor ligands are capable of forming shared electron bonds but not a formal covalent linkage with the metal. The monocyclopentadienyl and monocyclopentadienyl groups substituted for use with the present invention are more specifically illustrated by the formula: wherein: R ', in each occurrence, is independently selected from hydrogen, halogen, R, N-Rz, P-Rs; OR; SR or BR2, wherein R is as previously defined, or one or two pairs of adjacent hydrocarbyl groups R 'are linked together to form a molten ring system. Preferably, R 'is alkyl or haloalkyl up to 6 carbon atoms. What is most preferred of all is that Cp is cyclopentadienyl or pentamethylcyclopentadienyl. Illustrative, but not limiting, examples of the metal complexes that can be used in the preparation of the compounds of this invention are titanium, and zirconium derivatives. Titanium is the preferred metal. Highly preferred metal complexes comprise dialkoxides of 1 to carbon atoms of cyclopentadienyl titanium or dialkoxides of 1 to 4 carbon atoms of pentamethylcyclopentadienyl titanium. In a highly preferred embodiment of the present invention, Cp is β? -syclopentadienyl or nB pentamethylcyclopentadienyl, m is one, M is titanium, p is zero X is methoxide. Suitable d-cation activating, cocatalyst-forming cocatalysts include the salts of a Bronsted acid, an inert, non-coordinating anion (A-), as well as cationic oxidants, such as silver or ferrocenium salts, where the anion is said anion non-coordinating, inert. The term "inert" means that it does not interfere with the desired preparation of the catalyst or with the use of the compound containing the resulting metal complex with a polymerization catalyst. The term "compatible, non-coordinating anion means an anion that does not coordinate with the first component a derivative thereof, or that only weakly coordinates with that component, thus remaining sufficiently labile to be displaced by the aromatic vinylidene monomer qu to be polymerized The term "compatible anion, n coordinator" refers specifically to an anion which, when functioning as a charge-balancing anion in the catalyst system of this invention, does not transfer an anionic substituy or fragment thereof to the cationic portion of the anion. Catalyst The compatible anions are also anions that do not degrade to neutrality under the reaction conditions of the present invention The preferred non-coordinating, inert anions are those of the formula BX "4, where X" is a group fluorinated aryl, especially pentafluorophenyl. The preferred salts of the Bronsted acids are substituted tertiary ammonium salts, especially tet trimethylammonium aquisperfluorophenylborate tetrakisperfluorophenylborate of N, N-dimethylanilinium. The preferred cationic oxidizers are ferrocenium tetrakisperfluorophenylborate silver tetrakisperfluorophenylborate ferrocenium. Suitable organometallic hydrocarbylating agents include the metals of groups 1, 2 or 13 of the Periodic Table, substituted with hydrocarbyl of 1 to 10 carbon atom and zinc, especially the trialkyl aluminum compounds of 1 to 4 carbon atoms in the alkyl. Examples include triethylaluminum, tri-n-propylaluminum triisopropylaluminum, tri-n-butylaluminum, triisobutylalu iny and mixtures thereof. It is believed that the resulting cationic catalytic species is formed (without accepting to be bound by such belief) by the action of the hydrocarbylation agent to first replace a hydrocarbyloxy d ligand of the metal complex, followed by protonation by the acid salt of the metal complex. Bronsted or the molecular oxidation of the resulting complex, by the cationic oxidizer. Consequently, the resulting complex corresponds to the formula: CCpmMXn-? X '? > ] - A- where Cp, M, X, X ', m, n, p and A ~ are as previously defined. The catalyst can be prepared in a suitable solvent diluent at a temperature within the approximate range of -100 ° C to 300 ° C. The catalyst system can also be formed in situ if its components are added directly to the polymerization process and a suitable solvent or diluent, including a monovinylidene aromatic monomer, is used in said polymerization process. However, it is preferred to form the catalyst in a separate step before adding it to the polymerization reactor. The catalyst components are generally sensitive to both moisture and oxygen and must be transferred in an inert atmosphere, such as nitrogen, argon or helium. Suitable diluents for the catalyst preparation and for the polymerization include any of the compounds known in the prior art including, without necessarily being limited thereto, straight and branched chain hydrocarbons, such as alkanes of 6 to 20 carbon atoms. carbon (hexane, heptane, octane and mixtures thereof); cyclic and alicyclic hydrocarbons of 6 to 20 carbon atoms, such as cyclohexane, cycloheptane, methylcyclohexane, methylcycloheptane and mixtures thereof, the aromatic compounds of 6 to 20 aromatic carbon atoms substituted with alkyl, of 6 to 20 carbon atoms. , such as benzene, toluene, xylene, decalin mixtures thereof. Mixtures of the above diluents can also be used. The catalysts can be employed as homogeneous catalysts or can be supported on the surface of a suitable support such as alumina, silica or polymer. In the practice of the present invention, suitable vinylidene aromatic monomers include those represented by the formula: (R * > 5 - li ¬ wherein each R * is independently hydrogen, an aliphatic, cycloaliphatic or aromatic hydrocarbon group, having from 1 to 10 carbon atoms, better still, from I to 6 carbon atoms, and most suitable from 1 to 4 carbon atoms; carbon, or halogen atom. Examples of such monomers include styrene, chlorostyrene, n-butyl styrene, p-vinyltoluene, methylstyrene, etc., styrene being especially suitable. Styrene copolymers and the above vinylidene aromatic monomers, other than styrene, can also be prepared. Polymerization can be carried out under polymerization conditions in slurry, bulk or suspension, or under other suitable reaction conditions including reaction conditions of powdered solids. S can carry out the polymerization at temperatures of 0 I60 ° C, preferably from 25 to 100 ° C, better still, from 30 to 80 ° C for a sufficient time to produce the desired polymer. Typical reaction times are from a minute to 100 hours preferably from 1 to 10 hours. The optimum reaction time the residence time in the reactor will vary depending on the temperature, the diluent and other reaction conditions used. Subatmospheric pressure polymerization as well as superatmospheric pressure can be carried out suitably at a pressure within the 6.9 kPa 3,400 kPa scale. The use of environmental or low pressures, for example, from 6.9 to 34.5 kPa is preferred in view of the lower costs of capital and equipment. The polymerization can be carried out in the presence of an inert diluent or solvent or in the absence of them, in the presence of an excess of monomer. Suitable amounts of solvent or diluent are used to provide monomer concentration of 5% to 100% by weight. The molar ratio of the aromatic monomer of vinylidene to metal complex can vary from 100: 1 to 10 10: 1, preferably from 1000: 1 to 1 x 10ß: 1. The molar proportions of hydrocarbylating agent: metal complex preferably should be in the range of 2: 1 to 100: 1 preferably 10: 1 to 50: 1. As in other similar polymerizationsIt is highly desirable that the monomers and solvents used be of a sufficiently high purity that deactivation of the catalyst does not occur. Any suitable technique for the purification of monomers, such as devolatilization, reduced pressures or contact with molecular sieves or co-alumina of large surface area, can be employed. The purification of the resulting polymer to remove the entrained catalyst may also be convenient for the practitioner. Such contaminants can generally be identified by ash residues by polymer pyrolysis, which are attributable to residual metal complex or residual values of the hydrocarbylation agent. A suitable technique for eliminating said compounds is by solvent extraction, for example, extraction using chlorinated solvents of high boiling point, acids or bases, such as an aqueous caustic, followed by filtration. Having described the invention, the following examples are provided as an additional illustration and should not be considered as limitation. Unless otherwise indicated, all parts and percentages are based on weight.

EXAMPLES 1 TO R All reaction reactions were carried out under an inert atmosphere in a dry box. The solvent and styrene monomer were purified by bubbling Ns and passing through activated alumina and handled using normal inert atmosphere techniques. Catalytic solutions were prepared in volumetric flask, using toluene solvent. The required amount of N, N-dimethylanilinium tetraquaspentafluorophenylborat [CßHsN (CHs) 2H3? - [B (CßFe) 4] - was weighed and added to the flask. Then s added different amounts of 1 molar solution of tri-n-propylaluminium (TNPA) / toluene. To this mixture was added the required amount of metal complex, dimethoxide d pentamethylcyclopentadienyl-titanium (III), 0.03M in toluene. then toluene was added to the label of the volumetric flask. The final concentration of the titanium complex the ammonium salt activator was 0.003 molar. Blister sealed polymerizations were carried out by crimping, with capped septum. The ampoules were charged with 10 ml of styrene and various amounts of the catalyst solution. The ampoules were then sealed and equilibrated at 70 ° C in a water bath. The polymerization is quenched by the addition of methanol after a few hours of polymerization time. Each polymer sample was isolated and dried in order to determine the percent conversion. The molecular weight of the resulting syndiotactic polymer was determined by means of viscosity in common solution and current, using standards of atactic polystyrene. All polymers had melting points of more than 260 ° C consistent with tacticities of more than 50 percent, co base in a racemic triad. The results are shown in table I.

TABLE I ? jem trialquil- Molar ratio of% of con-plo. aluminum styrene: Al: T, i version 1 TNPA 200,000: 3: 1 31 2 id. 200,000: 5: 1 49 3 id 200,000: 10: 1 48 4 id 200,000: 15: 1 54 TABLE I (cont.) A trialkyl molar proportion of% of con-plo. aluminum estirenQ.LAl..Ti version 5 id 200,000: 20: 1 58 6 id 200,000: 30: 1 55 The use of pentamethyl clopentadienyl titanium (III) dimethoxide catalyst in combination with a trialkylaluminum hydrocarbylation agent d and a cation forming cocatalyst is seen to be extremely effective for the polymerization of aromatic vinylidene monomers to prepare syndiotactic polymers from from them.

EJKMPG, COMPARATIVE OS I AND 2.

The reaction conditions of Example 1 were substantially repeated, using dimethoxide d-pentamethylcyclopentadienyl-titanium (III) and N, N-dimethylanilinium tetrakine pentafluorophenyl-borate without a d-hydrocarbylation agent. The results are contained in quad II: TABLE II Opera- Time% molar ratio of with CLÓJ, (hours.) Estir.eno: Al: Ti versi n, 1 2 200,000: 0: 1 1 2 1 175,000: 0: 1 3 The above results indicate that poor yields are obtained in the absence of the hydrocarbylation agent.

The reaction conditions of Example 1 were substantially repeated, using dimethoxide d-pentamethylcyclopentadienyl-titanium (III) catalyst and N, N-dimethylanilinium tetrakispentafluorophenylborate cocatalyst. S added the tri-n-propylaluminum hydrocarbylating agent to styrene monomer, thereby simulating the desired catalyst formation in situ. The results are contained in table III.

TABLE III Example - Molar proportion of% of consumption. eatire.no: TNP; i: ~ version. 7 200,000: 70: 1: 1 37

Claims (8)

NOVELTY of the INVENTION CLAIMS

1. - A process for preparing syndiotactic polymers of vinylidene aromatic monomers, characterized in that it comprises contacting one or more vinylidene aromatic monomers, under polymerization conditions, with a catalytically effective amount of a catalyst comprising: (1) a metal complex which corresponds to the formula: CpmMXnX'p wherein: Cp is a 23B-substituted cyclopentadienyl e-cyclopentadienyl group; M is a metal of group 4 or of the lanthanide series of the Periodic Table, in the oxidation state +3 X, in each occurrence, is OR, wherein R and hydrocarbyl of 1 to 20 carbon atoms; X 'is a neutral, inert donor ligand; m and p are independently 0 or 1; n is an integer greater than or equal to 2; and the sum of m and n is 3; (2) an activating cocatalyst, cation former, comprising a non-coordinated, inert anion; Y . (3) an organometallic hydrocarbylation agent; the molar ratio of monovinylidene aromatic monomer being: metal complex of 100: 1 to 1 x 10: 1, the molar ratio of metal complex hydrocarbylation agent being from 2: 1 to 100: 1.

2. The process according to claim 1, further characterized in that the aromatic vinylidene monomer is represented by the formula: wherein each R * is independently hydrogen, an aliphatic, cycloaliphatic or aromatic hydrocarbon group having d 1 to 10 carbon atoms, or a halogen atom.

3. The process according to claim 2, further characterized in that the vinylidene aromatic monomer is styrene.

4. The process according to claim 1, further characterized because Cp corresponds to the formula: wherein: R ', _ in each occurrence, was independently selected from hydrogen, halogen, R, N-R2, P-Rz; Or SR or BR ?, where R is as previously defined, or one or two pairs of adjacent hydrocarbyl groups R 'are bonded together to form a molten ring system.

5. The process according to claim 1, further characterized in that M is titanium.

6. The process according to claim 5, further characterized in that Cp is? S-cyclopentadienyl or n & pentamethylcyclopentadienyl; m is 1, n is 2, p is zero and X and alkoxy of 1 to 4 carbon atoms.

7. The process according to claim 1, further characterized in that the catalyst comprises the reaction product of a dialkoxide of 1 to 4 carbon atoms of pentamethylcyclopentadienyl-titanium or dialkoxide of 4 carbon atoms of cyclopentadienyl-titanium; or trialkylaluminum of 1 to 4 carbon atoms, tetra-trimfluorophenylborate trimethylammonium, tetrakyl perfluorophenylborate of N, N-dimethylanilinium, tetrakisperfluo-rofenylborate of silver or tetrakisperfluorophenylborate of ferrocenium.

8. The process according to claim 7, further characterized in that the catalyst comprises the reaction product of pentamethylcyclopentadienyl-titanium trimethoxide, tri-n-propylaluminium and N, -dimethylanilinium tetrakanophenylborate. In testimony of which I sign the above in this city of Mexico, D.F., on the 7th day of the month of October 1994. BY THE DOW CHEMICAL COMPANY Ing. Javier Saucedo C,