Preparation of co-polymers of carbon monoxide and ethylenically unsaturated compounds

Abstract: A process for the preparation of co-polymers of carbon monoxide and one or more ethylenically unsaturated compounds by reacting the monomers under polymerization conditions in the presence of a catalyst system based on a) a source of cations of one or more metals of Group VIII of the Periodic Table, and b) a source of anions, in the further presence of a diluent in which the co-polymers are insoluble or virtually insoluble and of a minor amount of one or more non-ionic surfactants selected from alkoxylates of a monohydric alcohol and polymers of a vinyl amide monomer.

Description: The invention relates to a process for the preparation of co-polymers of carbon monoxide and one or more ethylenically unsaturated compounds. Linear co-polymers of carbon monoxide with one or more ethylenically unsaturated compounds, in which co-polymers the units originating from carbon monoxide on the one hand and the units originating from the ethylenically unsaturated compound(s) used on the other hand occur in a substantially alternating arrangement, can be prepared by contacting the monomers at an elevated temperature and pressure, in the presence of a diluent in which the co-polymers are insoluble or virtually insoluble, with a suitable catalyst. The preparation of the co-polymers can, in principle, be carried out in two manners, viz. batchwise or continuously. Batchwise preparation of the co-polymers is generally carried out by introducing catalyst into a reactor containing diluent and monomers and which is at the desired temperature and pressure. As polymerization proceeds, the pressure drops, the concentration of the co-polymers in the diluent increases and the viscosity of the suspension rises. The reaction is discontinued when the viscosity becomes very high because of severe agglomeration of co-polymer particles and further continuing could create difficulties in view of poor heat transfer in the suspension and stirring problems. In principle, the only parameter which remains constant in batchwise co-polymer preparation is the temperature. A variant of batchwise co-polymer preparation is semi-batchwise preparation in which besides the temperature also the pressure is kept constant by adding monomers to the reactor during the polymerization. In continuous co-polymer preparation, a diluent, monomers and catalyst are continuously added to a reactor containing monomers and a certain volume of the diluent and which is at the desired temperature and pressure and a co-polymer suspension is continuously withdrawn from it. During the continuous co-polymer preparation, the temperature, the pressure and the liquid volume in the reactor are kept substantially constant. After a start-up period in which the co-polymer concentration in the suspension increases to the desired value, a stationary state is reached which is characterized, inter alia, by the suspension withdrawn from the reactor having a substantially constant co-polymer content and the co-polymers contained therein having substantially constant properties. One of the important properties of the co-polymers in question is the bulk density. This plays an important role both in the preparation and in the treatment, storage, transport and processing of the co-polymers. As far as co-polymer preparation is concerned, the rule of thumb is that the maximum permissible suspension concentration, expressed in (kg co-polymer/kg suspension) x 100, is about one tenth of the bulk density expressed in kg/m 3 . This means that in the preparation of a co-polymer with a bulk density of 100 kg/m 3 , the maximum suspension concentration is about 10%, whereas in the preparation of a co-polymer with a bulk density of 200 kg/m 3 , the maximum suspension concentration is about 20%. Hence a doubling of bulk density offers the possibility of preparing about twice the quantity of co-polymer in the same reactor volume. As far as co-polymer treatment, such as filtering, washing and drying, is concerned, the quantity of adhering liquid is largely determined by the co-polymer bulk density. Thus it has been found, for example, that a co-polymer with a bulk density of 100 kg/m 3 binds approx. 5 kg diluent or washing liquid per kg, whereas to a co-polymer with a bulk density of 200 kg/m 3 considerably less liquid is bound. This is naturally of great importance on account of the quantity of liquid that must be used in washing the co-polymers and must be removed when the co-polymers are dried. As far as transport and storage are concerned, the rule is that the higher the co-polymers' bulk density, the more attractive the flow behaviour they will have and the less space they will occupy. As regards the processing of the co-polymers into shaped objects, it is often the case that co-polymers with low bulk density cause problems in the processing apparatus. For co-polymers with low bulk density, e.g. of below 250 kg/m 3 , a compacting treatment, for example by extrusion, in order to make them suitable for further processing in the usual equipment for that purpose,could form a problem. The higher the co-polymers' bulk density, the easier the prior treatment of the material, in particular an extrusion, will be. It will be clear from the above that the main interest is in a process whereby a relatively high suspension concentration is achieved and whereby co-polymers having a high bulk density are produced. However, a complication is formed by the above-mentioned agglomeration of co-polymer particles, which may occur, before the suspension concentration has reached a value required for obtaining co-polymers in an adequate yield. An investigation of this phenomenum has revealed that the moment of severe agglomeration can be somewhat postponed by increasing the amount of catalyst used. However, in particular when operating the process on technical scale, for economic reasons the use of larger quantities of catalyst is undesirable. Surprisingly it has now been found that there is a very narrow class of surface active compounds which, when present in a minor amount in the reaction mixture of the preparation of the co-polymers, delay the agglomeration of co-polymer particles, substantially without adversely effecting the rate of polymerization and the properties of the co-polymers obtained, such as their heat stability. This narrow class of surface active compounds comprises non-ionic surfactants selected from alkoxylates of a monohydric alcohol and polymers of a vinyl amide monomer. The use of other surface active compounds does not lead to the desired delay of agglomeration, and/or it leads to a lower polymerisation rate and/or, quite unexpectedly, to an appreciable decrease of the heat stability of the co-polymers prepared. The invention therefore relates to a process for the preparation of co-polymers of carbon monoxide and one or more ethylenically unsaturated compounds by reacting the monomers under polymerization conditions in the presence of a catalyst system based on a) a source of cations of one or more metals of Group VIII of the Periodic Table, and b) a source of anions, in the further presence of a diluent in which the co-polymers are insoluble or virtually insoluble and of a minor amount of one or more non-ionic surfactants selected from alkoxylates of a monohydric alcohol and polymers of a vinyl amide monomer. The metals of Group VIII of the Periodic Table include the noble metals palladium, rhodium, osmium, ruthenium, iridium and platinum and the metals of the iron group consisting of iron, cobalt and nickel. Of these, palladium, nickel and cobalt are preferred, in particular palladium. As source of cations of one or more of these metals conveniently a salt of the metal(s) selected, is used. Suitable salts include salts of mineral acids such as sulphuric acid, nitric acid and phosphoric acid and of sulphonic acids such as methane sulphonic acid, trifluoromethanesulphonic acid and para-toluene-sulphonic acid. Other suitable salts include salts of carboxylic acids, such as acetic acid, trifluoroacetic acid, propionic acid and citric acid. Furthermore, as cations source use may be made of the metals in their elemental form, or in a zero-valent state thereof, e.g. in complex form. Usually these sources are applied together with a protic acid, so that the metal cations are formed in situ. The source of anions (component b) on which the catalyst system of the invention is based, is conveniently an acid or salt thereof. A skilled person will appreciate that the anions of component b) are weakly or non-coordinating with the Group VIII metal cations. As suitable acids, the aforesaid acids participating in the Group VIII metal salts may be mentioned. Preferred anion sources are those from acids having a pKa value (measured at 18 °C in aqueous solution) of less than 4, in particular of less than 2. Preferred examples of anion sources are trifluoroacetic acid and p-toluenesulphonic acid and furthermore perchloric acid and tetrafluoroboric acid. Advantageously, the catalyst systems of the invention comprise, in addition to components a) and b), a stabilizing ligand, containing one or more sites which can form a complexing bond with a metal of Group VIII. Thus the ligands may be monodentate, bidentate or even tridentate. Bidentate ligands, containing two sites forming complexing bonds with a Group VIII metal are preferred. In particular preferred are bidentate ligands of the formula R 1 R 2 M 1 -R-M 2 R 3 R 4 wherein R 1 , R 2 , R 3 and R 4 independently represent optionally substituted hydrocarbylgroups, R represents a bivalent bridging group having 1 to 5 atoms in the bridge and M 1 and M 2 represent the same or different atoms selected from phosphorus, arsenic, antimony or nitrogen atoms. Preferably M 1 and M 2 both represent phosphorus atoms. R represents preferably a bivalent organic bridging group containing at least two carbon atoms in the bridge, in particular three carbon atoms. The optionally substituted hydrocarbylgroups R 1 , R 2 , R 3 and R 4 may be aryl, alkyl, alkaryl, aralkyl or cycloalkyl groups. Preferably they represent arylgroups and in particular aryl groups substituted by one or more polar groups such as alkoxy, alkylamino and dialkylamino groups and halogen atoms. Most preferred are phenyl groups wherein one or both ortho positions with respect to M 1 or M 2 , are substituted with an alkoxy group, preferably a methoxy group. Examples of suitable monodentate ligands may be indicated by the formula M 3 R 1 R 2 R 3 wherein M 3 represents a phosphorus, arsenic or antimony atom and R 1 , R 2 and R 3 have the aforesaid meaning. The amount of catalyst used in the process of the invention may vary considerably. Advantageously an amount is applied in the range of 10 -7 to 10 -1 gramatom of Group VIII metal(s) per mole of ethylenically unsaturated compound to be polymerized. Preferably the amount is in the range of 10 -6 to 10 -2 on the same basis. The co-polymers of the invention are insoluble or at least virtually insoluble in many conventional liquid solvents and accordingly a large number of these liquids may serve as diluent in the process of the invention. Recommended diluents are polar organic liquids, such as ketones, ethers, esters or amides. Preferably a protic liquid is used such as monohydric or dihydric alcohols. Lower monohydric alcohols are preferred diluents, e.g. methanol, ethanol and butanol-1. Methanol is in particular preferred. Without wishing to be bound by any theory, it is believed that the surfactant(s) present in the process of the invention contribute to the sterical stability of the suspension. Conceivably, the surface area of co-polymer particles in the suspension is at least partly covered by surfactant molecules, which delays the agglomeration of the co-polymer particles until the suspension concentration has reached a value, significantly higher than would have been reached in the absence of surfactant(s). The surfactants according to this invention are non-ionic surfactants selected from alcoholalkoxylates and polymers of a vinyl amide monomer. Typically the alcoholalkoxylates are conceivably derived from 1,2-alkylene oxides, in particular ethene oxide or 1,2-propene oxide, and from monohydric alkanols or alkyl substituted phenols comprising an aromatic system of one or more rings, typically one ring, the monohydric alkanols and the alkyl substituted phenols having typically from 7 to 25 carbon atoms. Preferred non-ionic surfactants of this invention are alkanolethoxylates defined by the formula CH 3 -(CH 2 ) n -O(-CH 2 -CH 2 -O) m -H wherein n is an integer in the range of 8 to 18 and m is an integer in the range of 1 to 6. The representatives of this category comprise a non polar moiety conceivably derived from linear alkenes and a polar moiety conceivably derived from one or more ethylene oxide groups. Preferably the non-polar moiety comprises from 12 to 15 carbon atoms. The number of ethylene oxy groups involved in the polar moiety is preferably between 2 and 4, in particular 3. Many of these compounds are commercially available surfactants, such as DOBANOL 25-3 (Trade Mark). Other preferred non-ionic surfactants are alkylphenolalkoxylates such as nonylphenol ethoxylate - 10 EO (ethylene oxide) and nonylphenol ethoxylate - 20 EO, surfactants containing a branched non polar moiety and a polar moiety e.g. derived from (a number of) ethylene oxide groups. Examples of the polymers of a vinyl amide monomer are polyacrylamide, polymethacrylamide and polyvinylpyrrolidone, the latter being a preferred surfactant. The polymers of a vinyl amide monomer have typically a number average molecular weight in the range of from 5x10 3 to 10 6 , more typically in the range of from 5x10 3 to 10 5 . Very good results can be obtained with commercially available polyvinylpyrrolidone having a number average molecular weight of about 10000. In the process of the invention only minor amounts of surfactants are used. Generally the amount is well below 20 g per litre of reaction mixture, in most cases below 10 g on the same basis. Preferred amounts are in the range of 0.7 to 5 g per litre of reaction mixture. The surfactant(s) may be supplied to the reactor before the co-polymerization reaction starts, or during that reaction. If surfactants are supplied before, or at an early stage of the reaction, it is recommended to supply only a small portion of the total amount of surfactants intended to use. It is preferred to supply the surfactants during the process in equal, small increments or continuously to the reactor. Ethylenically unsaturated compounds, suitable to be used as starting material, include unsaturated compounds consisting exclusively of carbon and hydrogen and compounds comprising in addition one or more hetero-atoms, such as oxygen or nitrogen atoms. Examples are unsaturated esters, such as methyl acrylate and vinyl acetate. Unsaturated hydrocarbons are, however, preferred. Suitable examples are the lower olefins, such as ethene, propene and 1-butene, cyclic olefins such as cyclopentene and aryl-substituted olefins such as styrene. Ethene and mixtures of ethene and propene are in particular preferred starting materials. The molar ratio between the monomer reactants, viz. on the one hand carbon monoxide and on the other hand the ethylenically unsaturated compound(s), is advantageously selected in the range of 5:1 to 1:5, preferably in the range of 1.5:1 to 1:1.5, substantially equimolar amounts being most preferred. The reaction is generally performed at temperatures in the range of 20 to 180 °C and at pressures in the range of 2 to 150 bar. Preferred reaction temperatures are in the range of 30 to 150 ° C and preferred pressures are selected in the range of 20 to 100 bar. The co-polymers prepared according to the invention have established utility in various outlets for thermoplastics. They may be processed by means of conventional techniques into films, sheets, plates, fibres, shaped articles such as containers for food and drinks and parts for the car industry. The invention will now be illustrated by the following examples. Example 1 A carbon monoxide/ethene co-polymer was prepared as follows: An autoclave with a capacity of 3.78 l and equipped with a mechanical stirrer with 2 baffles, operated at 600 rpm, was charged with 1500 ml of methanol. The air present in the autoclave was removed therefrom by pressurizing the autoclave with carbon monoxide to 15 bar and then releasing the pressure. This procedure was repeated twice. Under stirring the contents of the autoclave were brought to a temperature of 86 °C and a 2:1 mixture of carbon monoxide and ethene was supplied until the pressure was 25 bar. Subsequently a catalyst solution was introduced consisting of 0.013 mmol palladium (II) trifluoroacetate (1.4 mg palladium), 0014 mmol 1,3-bis[bis(2-methoxyphenyl)phosphino] propane and 0.18 mmol trifluoroacetic acid (TFA). During the reaction period the temperature and pressure were kept constant. After seven runhours, 3 g of a surfactant, DOBANOL 25-3 (Trade Mark), a commercially available condensation product of a mixture of n-alkanols with 12 to 15 carbonatoms and on average 3 mol ethene oxide per mol alkanol, was added. As soon as agglomeration occurred, the formed suspension became stagnant and the process was discontinued. The contents of the autoclave were cooled to ambient temperature and the pressure was released. The results, as regards LVN of the co-polymer obtained, reaction period, suspension concentration and bulk density at the moment of agglomeration, are shown in the Table. LVN (limiting viscosity number) is the intrinsic viscosity, calculated from determined viscosity values, measured for different co-polymer concentrations in m-cresol at 60 °C. Example 2 A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example 1, with the difference that as surfactant 3 g of nonylphenol ethoxylate 10 EO (ethene oxide) was added, instead of DOBANOL 25-3. The results are shown in the Table. Example 3 A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example 1, with the difference that as surfactant 3 g of nonylphenol ethoxylate 20 EO was added, instead of DOBANOL 25-3. The results are shown in the Table. Example 4 A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example 1, with the difference that after 5, 6 and 27 runhours, respectively, portions of 0.5 g of polyvinylpyrrolidone (number average molecular weight 10000) were added as surfactant, instead of DOBANOL 25-3. The results are shown in the Table. Example A (for comparison) A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example 1, with the difference that as surfactant 3 g of tallow acid diethanolamide (TA DEA) was added, instead of DOBANOL 25-3. After the addition of surfactant complete deactivation of the catalyst was observed, whereupon the process was discontinued. Further details are shown in the Table. Example B (for comparison) A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example 1, with the difference that as surfactant 3 g of coconut fatty acid diethanolamide (C DEA) was added, instead of DOBANOL 25-3. After the addition of surfactant complete deactivation of the catalyst was observed, whereupon the process was discontinued. Further details are shown in the Table. Example C (for comparison) A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example 1, with the difference that after 5, 6 and 7 runhours, respectively, portions of 0.5 g of a block copolymer of 90 %w propylene glycol and 10 %w ethylene glycol (PO EO) were added as surfactant. The results are shown in the Table. Example D (for comparison) A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example 1, with the difference that no surfactant was added. The results are shown in the Table. Example E (for comparison) A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example D, with the difference that the amount of trifluoroacetic acid was 0.11 mmol, instead of 0.18 mmol. The results are shown in the Table. Example F (for comparison) A carbon monoxide/ethene co-polymer was prepared, substantially as described in Example D, with the difference that the amount of palladium was 0.7 mg, instead of 1.4 mg and the amount of trifluoracetic acid was 0.11 mmol, instead of 0.18 mmol. The results are shown in the Table.

Claims: A process for the preparation of co-polymers of carbon monoxide and one or more ethylenically unsaturated compounds by reacting the monomers under polymerization conditions in the presence of a catalyst system based on a) a source of cations of one or more metals of Group VIII of the Periodic Table, and b) a source of anions, in the further presence of a diluent in which the co-polymers are insoluble or virtually insoluble and of a minor amount of one or more non-ionic surfactants selected from alkoxylates of a monohydric alcohol and polymers of a vinyl amide monomer. A process as claimed in claim 1, characterized in that a catalyst system is used which is based on a source of cations of palladium as component a), and b, and in that the catalyst system contains in addition a diphosphine of the formula R 1 R 2 P-R-P-R 3 R 4 wherein R 1 , R 2 , R 3 and R 4 independently represent hydrocarbyl groups or hydrocarbyl groups substituted with one or more polar groups and R represents a bivalent bridging group containing at least two carbon atoms in the bridge. A process as claimed in claim 2, characterized in that in the bidentate ligand of the formula (I) R 1 , R 2 , R 3 and R 4 represent phenyl groups substituted at one or both ortho-positions by a polar group, in particular an alkoxy group, and R represents a bivalent bridging group containing 3 carbon atoms in the bridge. A process as claimed in any of claims 1-3, characterized in that as diluent an organic protic liquid is used. A process as claimed in claim 4, characterized in that as diluent a lower alcohol is used, in particular methanol. A process as claimed in any of claims 1-5, characterized in that as non-ionic surfactant one or more compounds of the formula CH 3 -(CH 2 ) n -O(CH 2 -CH 2 -O) m -H are used, wherein n is an integer in the range of 8 to 18 and m is an integer in the range of 1 to 6. A process as claimed in claim 6, characterized in that in the compounds of formula (II) n is an integer from 11 to 14 and m is 3. A process as claimed in any of claims 1-5, characterized in that as non-ionic surfactant poly(vinylpyrrolidine) is used having a number average molecular weight in the range of from 5x10 3 to 10 5 . A process as claimed in any of claims 1-8, characterized in that the amount of non-ionic surfactant(s) used is in the range of 0.7 to 5 g per litre of reaction mixture. A process as claimed in any of claims 1-9, characterized in that the surfactant(s) is (are) added to the reactor continuously during the process. A process as claimed in any of claims 1-10, characterized in that as ethylenically unsaturated compound ethene or a mixture of ethene and propene is used, the molar ratio between carbon monoxide relative to ethylenically unsaturated compound(s) being in the range of 1.5:1 and 1:1.5, and in that the reaction is carried out at a temperature in the range of 30 to 150 °C, at a pressure in the range of 20 to 100 bar and using a quantity of catalyst which contains 10 -6 to 10 -2 gramatom of Group VIII metal per mole of ethylenically unsaturated compound to be polymerized.

Inventors: MUIJS HERMAN MATHIEU, MULDER JAN HARM, SMEDT PHILIP JEAN MARIE MAURIC, MUIJS, HERMAN MATHIEU, MULDER, JAN HARM, SMEDT, PHILIP JEAN MARIE MAURICE
Applicants: SHELL INT RESEARCH, SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1993
Main classification: C08G67
IPC codes: C08G67