WO2000029462A1

WO2000029462A1 - Process for the preparation of polyketone polymers

Info

Publication number: WO2000029462A1
Application number: PCT/EP1999/009023
Authority: WO
Inventors: Andrew Neave Rogers; Wilhelmina Cornelia Verhoef-Van Wijk
Original assignee: Shell Internationale Research Maatschappij BV
Current assignee: Shell Internationale Research Maatschappij BV
Priority date: 1998-11-16
Filing date: 1999-11-12
Publication date: 2000-05-25
Anticipated expiration: 2001-05-16
Also published as: AU1967000A

Abstract

Process for the preparation of copolymers of carbon monoxide, ethene and optionally up to 5 wt.% based on total weight of polymer of a C3+ olefin, in which (copolymers) the units originating from carbon monoxide and the units originating from ethene or C3+ olefin occur in a substantially alternating order, said process comprising copolymerizing carbon monoxide, ethene and optionally C3+ olefin in the presence of a suitable catalyst composition comprising a Group VIII metal, wherein the molar ratio of carbon monoxide to ethene plus C3+ olefin is at most 0.25 during copolymerization and wherein the molar ratio of C3+ olefin to ethene is in the range of from 0 to 0.8.

Description

PROCESS FOR THE PREPARATION OF POLYKETONE POLYMERS

The present invention relates to a process for the preparation of poly etone polymers, m particular linear alternating copolymers of carbon monoxide (CO) , ethene and optionally an α-olefm containing at least three carbon atoms (C3+ olefms), such as e.g. propene, and to polyketone polymers obtainable by such process.

From EP-A-0, 246, 674 it is known to prepare linear alternating copolymers of carbon monoxide (CO) and ethene by polymerizing a mixture of CO and ethene at an overall pressure of between 75 and 250 bar and an ethene/CO partial pressure ratio of between 0.75 and 3 in the presence of a catalyst composition comprising:

(a) a palladium compound,

(b) an anion of an acid with a pKa of less than 2, provided the acid is not a hydrohalogenic acid, and

(c) a bidentate ligand of the general formula R!R²M-R-MR3R _{r w}herem M represents phosphorus, arsenic or antimony, R represents a bivalent bridging group containing at least two carbon atoms in the bridge connecting both atoms M and R¹, R² , R³ and R⁴ represent hydrocarbyl groups, which may or may not substituted with polar groups.

According to EP-A-0 , 2 6, 674 it was found that, contrary to expectations from earlier research, variation of the ethene/CO partial pressure ratio at a given high overall pressure had a substantial effect on the molecular weights of the polymers obtained. Polymers of considerably higher molecular weight were accordingly obtained when carrying out the polymerization at an ethene/CO partial pressure ratio between 0.75 and 3. In EP-A-0, 319, 083 a process for the preparation of polyketone polymers is disclosed, in which process a mixture of CO with one or more -olefins is polymerized at an olefin/CO partial pressure ratio of from 1 to 4. The catalyst composition used in this process comprises a palladium compound, an anion of an acid with a pKa of less than 6 and a phosphorus bidentate ligand of the general formula R1R²P-R-PR R4 _f wherein R represents a bivalent bridging group containing three atoms in the bridge connecting both phosphorus atoms and Έ - , R2 , R3 and R represent the same or different polar-substituted aryl groups, with each of these aryl groups containing at least one polar substituent in a position ortho with respect to the phosphorus atom bound to the aryl group concerned. The process disclosed in EP-A-0, 319, 083 is stated to lead to an increased reaction rate or molecular weight .

Although the processes disclosed in EP-A-0, 246, 674 and EP-A-0, 319, 083 attain the claimed results in terms of polymerization rate or molecular weight, it was found that the bulk density of the CO/ethene or CO/ethene/propene copolymers obtained was not sufficiently high. It would be very advantageous if a polyketone polymer could be provided having the desired molecular weight in combination with a high bulk density, while at the same time this polyketone polymer is produced at a commercially acceptable polymerization rate. In this connection it is important to note that the molecular weight of the CO/ethene or CO/ethene/C3+ olefin copolymers should not be too high as this would make extrusion of the polymers extremely difficult. If the molecular weight is too high, namely, extrusion has to take place under severe conditions in terms of temperature and extruder screw torque, which has an adverse effect on the properties of the extruded polymer. Due to the severe conditions applied, degradation of the polymer occurs . Lower molecular weight polymers have a lower melt viscosity resulting in a larger melt processing window. This is particularly important for certain application like compounding and moulding. On the other hand, the molecular weight should also not be too low, as this has a negative impact on particularly the mechanical properties of the polymer product. The present invention particularly focuses on

CO/ethene copolymers and CO/ethene/C3+ olefin copolymers having a C3+ olefin content of 5 wt% or less, more particularly 3.5 wt% or less, based on total weight of polymer. For these polyketone polymers it was found that the molecular weight expressed in terms of Limiting

Viscosity Number (LVN) should suitably be in the range of from 0.7 to 1.8 and more suitably 0.8 to 1.6 dl/g. In general, if a polyketone polymer exhibits a higher molecular weight its LVN is also higher. The concept of LVN is well known in the art and is extensively explained in e.g. the aforementioned EP-A-0, 246, 674 and EP-A-0, 319, 083. The LVN referred to in the present application corresponds with the LVN as explained in EP-A-0,319,083, i.e. an LVN on the basis of the viscosities determined at 60 °C of four solutions of the polymer prepared by dissolving the polymer in four different concentrations at 60 °C in m-cresol.

It was found that although CO/ethene copolymers and the aforesaid CO/ethene/C3+ olefin copolymers having an LVN in the range of from 0.7 to 1.8 dl/g could be produced with the known preparation processes, such copolymers which also have a desired high bulk density of at least 200 kg/m^ and more particularly of at least

290 kg/m^ could not be obtained with these processes. Especially copolymers of CO, ethene and up to 5 wt% of a C3+ olefin having a relatively low LVN in the range from 0.8 to 1.4 as well as a bulk density of at least

200 kg/m³ and more particularly of at least 290 kg/m³ have thus far not be obtained.

One reason why a high bulk density is desired is that it allows a higher suspension concentration during preparation of the polymer, thus enabling a higher production of polymer. Another advantage of a high bulk density is that during the work up of a polymer, a polymer with a high bulk density attaches much less washing liquid than a polymer with a lower bulk density. A still further advantage of a high bulk density can be recognised in the processing of polymers into shaped products. Polymers with a low bulk density have been experienced to often give problems in the processing equipment, thus necessitating a compacting pretreatment .

Thus, the present invention aims to provide linear alternating copolymers of CO, ethene and optionally up to 5 wt% based on total weight of polymer of a C3+ olefin having both an LVN of from 0.7 to 1.8 dl/g and a bulk density of at least 200 kg/m^ as well as a process for the preparation of such copolymers, wherein these copolymers are produced at commercially acceptable polymerization rates.

It was found that applying a specific CO/olefin molar ratio, the aforesaid copolymers could be obtained at high polymerization rates.

Accordingly, the present invention relates to a process for the preparation of copolymers of carbon monoxide, ethene and optionally up to 5 wt% based on total weight of polymer of a C3+ olefin, in which copolymers the units originating from carbon monoxide and the units originating from ethene or C3+ olefin occur n a substantially alternating order, said process comprising copolymerizing carbon monoxide, ethene and optionally C3+ olefin in the presence of a suitable catalyst composition comprising a Group VIII metal, wherein the molar ratio of carbon monoxide to ethene plus C3+ olefin is at most 0.25 during copolymerization and wherein the molar ratio of C3+ olefin to ethene is in the range of from 0 to 0.8.

The molar ratio of CO to ethene plus C3+ olefin and the molar ratio of C3+ olefin to ethene are molar ratios

(or partial pressure ratios) between the monomers in the gas phase. Thus, in a liquid phase process these ratios apply to the composition of the gas phase above the liquid medium. In a gas phase process these ratios define the composition of the gas phase in the entire reactor volume .

The relatively low molar ratio of CO to ethene plus C3+ olefin (if any) of at most 0.25 is essential to the process according to the present invention. This molar ratio will not normally be lower than 0.01. Preferably, this molar ratio is between 0.04 and 0.2, while the most preferred ratio is in the range of from 0.05 to 0.15.

The polyketone polymers prepared in accordance with the present invention may contain up to 5 wt% and preferably from 0 to 3.5 wt% of C3+ olefin, said weight percentages being based on total weight of polymer. Very good results have been obtained for CO/ethene copolymers, so without any C3+ olefin, and with relatively small amounts (to a maximum of 5 wt%) of C3+ olefin being included in the polymer. The C3+ olefin suitably has up to 12 carbon atoms and may, for example, be selected from propene, butene, decene and dodecene. Of these, propene is preferred. The molar ratio of C3+ olefin to ethene should range from 0 to 0.8 and preferably has a value in the range of from 0 to 0.5.

The process according to the invention is suitably carried out at an overall pressure of from 20 to 150 bar. However, for economic reasons overall pressures between 20 and 75 bar are preferred. For the purpose of the present invention it was found that an overall pressure of from 30 to 60 bar was particularly suitable. The polymerization is suitably carried out at a temperature in the range of from 40 to 150 °C . However, within the context of the present invention it was found that temperatures in the range of from 50 to 90 °C are particularly preferred, whilst excellent results were achieved when applying temperatures of from 65 to 85 °C . Furthermore, it is preferred to carry out the polymerization in a diluent in which the CO/ethene copolymers formed are essentially insoluble such that they form a suspension. Very suitable diluents are lower (i.e. C1-C4) alcohols and in particular methanol. However, it will be understood that in certain embodiments the process according to the present invention may also be carried out as a gas phase process. In the process of the present invention a catalyst is used which is capable of catalysing the formation of linear alternating copolymers of CO, ethene and optionally C3+ olefin, starting from a mixture comprising these monomers. Such catalyst composition comprises a Group VIII metal originating from a compound of that Group VIII metal. Suitable catalysts are well known in the art and examples of such catalysts are described in e.g. the aforementioned EP-A-0, 246, 674 and EP-A-0, 319, 083 and in EP-A-0, 121, 965; EP-A-0, 181, 014 ; EP-A-0, 248 , 483; EP-A-0, 619,335 and in EP-A-0, 650, 761. The quantity of catalyst composition used in the process of the present invention suitably is such that per mole of ethene to be copolymerized 10^~7 to 10^~3 _and particularly 10^~ o 10^-4 gram atom of Group VIII metal is present. The polymerization process according to the present invention may be carried out either batchwise or continuously.

The Group VIII metal compound used in the catalyst composition may suitably be a nickel, cobalt or palladium compound, of which a palladium compound is preferred. A suitable palladium compound is a palladium salt of a carboxylic acid and in particular palladium acetate. A preferred catalyst composition comprises:

(a) a compound of a Group VIII metal as described hereinbefore,

(b) an anion which does not or only weakly co-ordinates with the Group VIII metal under the copolymerization conditions applied, and

(c) a bidentate ligand having two phosphorus, nitrogen, arsenic or antimony containing dentate groups via which the bidentate ligand can form a complex with the Group VIII metal.

The anion used as component (b) should not or only weakly co-ordinates with the Group VIII metal under the copolymerization conditions applied. Examples of suitable anions are protic acids, including acids which are obtainable by combining a Lewis acid and a protic acid, and acids which are adducts of boric acid and a 1,2-diol, a catechol or a salicylic acid. Preferred acids are those acids which have a pKa of less than 6, in particular less than 4, more in particular less than 2, when measured in an aqueous solution at 18 °C. Examples of suitable acids are known in the art and include sulphuric acid, perchloric acid, sulphonic acids, such as methane sulphonic acid and para-toluenesulphonic acid, and carboxylic acids, such as 2, 6-dihydroxybenzoic acid, maleic acid, trichloroacetic acid, difluoroacetic acid and trifluoroacetic acid. Trifluoroacetic acid is a preferred acid. Examples of combinations of Lewis acids with a protic acids are tetrafluoroboric acid and hexafluoroboric acid. Other suitable anions are borate anions comprising the same or different hydrocarbyl groups attached to boron. Tetraarylborates and carborate are preferred. Hydrocarbylboranes, such as e.g. triphenylborane, or aluminoxanes, such as methyl aluminoxanes and tert-butyl aluminoxanes, may also be applied as compounds functioning as a source of anions . More examples of suitable anions are given in EP-A-0,743,336.

The quantity of the source of anions is suitably selected such that it provides in the range of from 0.5 to 50, preferably from 0.1 to 25, equivalents of anions per gram atom of Group VIII metal. However, aluminoxanes may be used in such a quantity that the molar ratio of aluminium to the Group VIII metal is in the range of from 4000:1 to 10:1, preferably from 2000:1 to 100:1, most preferably from 500:1 to 200:1.

Organic oxidant promoters may be incorporated into the catalyst composition in order to enhance their performance. Examples of suitable promoters are quinones, such as benzoquinone, naphthoquinone and anthraquinone . The amount of promoter used is suitably in the range of from 1 to 50, preferably 1 to 10, mole per gram atom of Group VIII metal.

The bidentate ligand contains two phosphorus, nitrogen, arsenic or antimony containing dentate groups via which the bidentate ligand can form a complex with the Group VIII metal. Suitable bidentate ligands are those of the general formula R!R2M-R-MR3R4 _r wherein R¹, R² , R3 and R^ represent the same or different aryl groups, which may be either unsubstituted or substituted with one or more polar or apolar groups, M represents phosphorus, nitrogen, arsenic or antimony and R represents a bivalent bridging group. It is preferred that in the above general formula M represents phosphorus, R1, R², R3 _and R^ independently represent a phenyl group or a polar-substituted phenyl group and R represents a bivalent organic bridging group having at least two atoms in the bridge connecting the two phosphorus atoms .

In a very much preferred embodiment R^, R², R and R^ are all the same and represent a polar-substituted phenyl group, wherein the polar substituent suitably is an alkoxy group, most suitably a methoxy group. In addition to a polar substituent an apolar substituent, in particular a methyl group, may be present. Examples of suitable polar-substituted groups are 2-methoxyphenyl, 2, 4-dimethoxyphenyl, 4-methoxyphenyl, 2, 6-dimethoxy- phenyl, 2-methoxy-5-methylphenyl and 2 , 4 , 6-trimethoxy- phenyl . Of these, 2-methoxyphenyl is preferred. The bridging group R preferably is a bivalent bridging group containing at least two carbon atoms in the bridge connecting both atoms M. Suitably, the bridging group contains three or four atoms in the bridge connecting the two atoms M, whereby the bridge may contain substituents or even side chains or whereby two adjacent atoms in the bridge may form part of a cyclic structure. The atoms forming the bridge may be carbon atoms, but may also include one or more nitrogen atoms. Examples of suitable bridging groups R containing three atoms in the bridge are the -CH2-CH₂-CH₂- group, the -CH₂-C (CH₃) ₂-CH₂- gr p, the -CH₂-C(C₂H₅)2-CH₂- group and the -CH₂-Si (CH₃) - • group. An example of a cyclic bridging group is a dioxolane bridge, while an example of a bridging group containing four atoms in the bridge is the -CH₂-CH₂-CH₂- CH₂- group. Examples of very suitable bidentate ligands useful as component (c) in the catalyst composition to be used are: 1 , 3-bis (diphenylphosphino) propane 1, 3-bis [bis (2-methoxyphenyl) phosphino] propane 1, 3-bis [bis (2, 4-dimethoxyphenyl) phosphino] propane 1 , 3-bis [bis (2 , 6-dimethoxyphenyl) phosphino] propane and

1, 3-bis [bis (2-methoxy-5-methylphenyl) phosphino] propane . Of these, 1, 3-bis [bis (2-methoxyphenyl) phosphino] propane is particularly preferred. The bidentate ligands are suitably used in the catalyst composition in a quantity of from 0.5 to 2 and in particular of from 0.75 to 1.5 mole per gram atom of Group VIII metal.

When a nitrogen bidentate ligand is used, preference is given to compounds of the general formula X X / \ / \ N = C - C = N wherein X represents an organic bridging group containing three or four atoms in the bridge at least two of which are carbon atoms, such as 2 , 2 ' -bipyridine and 1,10- phenanthroline .

If the process according to the present invention is carried out in a liquid medium, a seed material may suitably be applied. Such seed material typically is a finely dispersed solid material, which is present in the reactor at the start of the polymerization. Both organic and inorganic materials can be used for this purpose. Preferably, a polymer is used and in particular an alternating copolymers of carbon monoxide with one or more ethylenically unsaturated monomers, particularly α- olefins. Examples include CO/ethene/propene terpolymers and CO/ethene copolymers. If used, the amount of seed material present at the start of the polymerization may suitably range from 1 to 15 wt% based on weight of diluent present in the reactor. More preferably, the seed material is used in an amount of from 2 to 10 wt%.

In a further aspect the present invention relates to copolymers of carbon monoxide, ethene and up to 5 wt% of C3+ olefin, in which copolymers the units originating from carbon monoxide and the units originating from ethene or C3+ olefin occur in a substantially alternating order and which copolymers have an LVN in the range of from 0.7 to 1.8 dl/g and a bulk density of at least

200 kg/m³. Preferably, the copolymers have an LVN in the range of from 0.8 to 1.6 dl/g, more preferably 0.8 to 1.4 dl/g, and a bulk density in the range of from 290 to 450 kg/m .

It was found that these copolymers exhibit an excellent behaviour in terms of processing characteristics.

The invention is further illustrated by the following examples . Example 1

A CO/ethene copolymer was prepared as follows. A mechanically stirred autoclave with a volume of

3.8 litres was charged with 1.5 litre of methanol and 75 grams of CO/ethene/propene seed material. After the contents of the autoclave were brought to a temperature of 81 °C, ethene and CO were introduced in such amounts that the CO/ethene partial pressure ratio was 0.1 and the total pressure was 46 bar. Subsequently, a catalyst solution was introduced into the autoclave, which consisted of: 6.2 ml acetone 0.055 mmol palladium acetate

0.032 mmol 1 , 3-bis [bis (2-methoxyphenyl) phosphino] propane

0.33 mmol trifluoroacetic acid.

The pressure inside the autoclave was maintained at 46 bar by charging a 1:1 mixture of CO and ethene. The uptake of feed gas was measured by a calibrated mass-flow censor in the feed-line. After 6 hours the reaction was terminated by venting the unreacted gases and by stopping the heating. The product slurry was filtered and dried in a vacuum oven at 70 °C for 4 hours.

The polymerization rate, calculated on the basis of the CO/ethene copolymer formed, amounted 8.11 kg copolymer/g palladium. hour . The CO/ethene copolymer had an LVN of 0.90 dl/g and a bulk density of 228 g/ml. Example 2

Example 1 was repeated except that the CO/ethene molar ratio during copolymerization was 0.05 instead of 0.1.

The polymerization rate, calculated on the basis of the CO/ethene copolymer formed, amounted 4,28 kg copolymer/g palladium. hour and the CO/ethene copolymer had an LVN of 0.79 dl/g and a bulk density of 321 g/ml. Example 3

Example 1 was repeated except that the CO/ethene molar ratio during copolymerization was 0.25 instead of 0.1.

The polymerization rate, calculated on the basis of the CO/ethene copolymer formed, amounted 8.4 kg copolymer/g palladium. hour and the CO/ethene copolymer had an LVN of 1.5 dl/g and a bulk density of 210 g/ml. Comparative Example 1

Example 1 was repeated except that the CO/ethene molar ratio during copolymerization was 0.5 instead of 0.1. The polymerization rate, calculated on the basis of the CO/ethene copolymer formed, amounted 10.6 kg copolymer/g palladium. hour and bulk density was 255 g/ml. The LVN, however, was as high as 2.1 dl/g. Example 4

A CO/ethene/propene copolymer was prepared as follows. A mechanically stirred autoclave with a volume of 3.8 litres was charged with 1.5 litre of methanol and 75 grams of CO/ethene/propene seed material. After the contents of the autoclave were brought to a temperature of 79 °C, CO was introduced first followed by 129 grams propene and finally ethene was introduced to reach a total pressure of 47.5 bar. The CO/olefin partial pressure ratio was 0.1 and the propene/ethene partial pressure ratio was 0.29. Subsequently, the same catalyst solution as used in Example 1 was introduced into the autoclave .

The pressure inside the autoclave was maintained at 47.5 bar by charging a 1:1 mixture of CO and ethene. The uptake of feed gas was measured by a calibrated mass-flow censor in the feed-line . After 6 hours the reaction was terminated by venting the unreacted gases and by stopping the heating. The product slurry was filtered and dried in a vacuum oven at 70 °C for 4 hours. The CO/ethene/propene copolymer was obtained at a rate of 5.7 kg copolymer/g palladium. hour and had a melting point of 243 °C, an LVN of 1.32 dl/g and a bulk density of 298 g/ml.

Claims

C L I S

1. Process for the preparation of copolymers of carbon monoxide, ethene and optionally up to 5 wt% based on total weight of polymer of a C3+ olefin, in which copolymers the units originating from carbon monoxide and the units originating from ethene or C3+ olefin occur in a substantially alternating order, said process comprising copolymerizing carbon monoxide, ethene and optionally C3+ olefin in the presence of a suitable catalyst composition comprising a Group VIII metal, wherein the molar ratio of carbon monoxide to ethene plus C3+ olefin is at most 0.25 during copolymerization and wherein the molar ratio of C3+ olefin to ethene is in the range of from 0 to 0.8.

2. Process according to claim 1, wherein the molar ratio of carbon monoxide to ethene plus C3+ olefin during copolymerization is between 0.04 and 0.2.

3. Process according to claim 1 or 2, wherein the polymerization is carried out at a temperature in the range of from 50 to 90 °C and at an overall pressure between 20 and 75 bar.

4. Process according to any one of claims 1-3, wherein the catalyst composition comprises:

(a) a compound of a Group VIII metal,

(c) a bidentate ligand having two phosphorus, nitrogen, arsenic or antimony containing dentate groups via wh^; the bidentate ligand can form a complex with the Gr< ' VIII metal.

5. Process according to claim 4, wherein the Group VIII metal is palladium.

6. Process according to claim 4 or 5, wherein the anion of component (b) is an anion of an acid having a pKa of less than 6.

7. Process according to any one of claims 4-6, wherein the bidentate ligand is a bidentate ligand of the general formula R!R²M-R-MR³R⁴ , wherein R¹, R², R³ and R⁴ represent the same or different aryl groups, which may be either unsubstituted or substituted with one or more polar or apolar groups, M represents phosphorus, nitrogen, arsenic or antimony and R represents a bivalent bridging group.

8. Process according to claim 7, wherein in the general formula of the bidentate ligand M represents phosphorus,

R1, R² , R3 and R⁴ independently represent a phenyl group or a polar-substituted phenyl group and R represents a bivalent organic bridging group having at least two carbon atoms in the bridge connecting the two phosphorus atoms.

9. Copolymer of carbon monoxide, ethene and up to 5 wt% of C3+ olefin, in which copolymers the units originating from carbon monoxide and the units originating from ethene or C3+ olefin occur in a substantially alternating order and which copolymers have an LVN in the range of from 0.7 to 1.8 dl/g and a bulk density of at least

200 kg/m³.

10. Copolymer according to claim 9 comprising up to 3.5 wt% of C3+ olefin and having an LVN in the range of from 0.8 to 1.8 dl/g and a bulk density in the range of from 290 to 450 kg/m³.