NL8801276A - Suspension copolymerisation of carbon mon:oxide and olefinic cpd. - using palladium catalyst with sepn. of polymer into small particles rich in palladium and larger particles lean in palladium - Google Patents

Abstract

In prepn. of polymers, a mixt. of CO and an olefinically unsatd. cpd. is polymerised by contact, at raised temp. and pressure, with a compsn. contg. a soln. of a catalyst compsn. contg. Pd in a diluent in which the polymer is (almost) insol. The polymer prod. comprising Pd-contg. polymer particles with a range of particle size, is sepd., w.r.t. particle size, into (i) a Pd-rich by-prod. fraction contg. the smaller particles, and forming at least 10 wt.% of total polymer, and (ii) a Pd-lean main prod. fraction contg. the larger particles.

Description

T 315 NET

PREPARATION OF POLYMERS *

The invention relates to a process for the preparation of polymers of carbon monoxide with one or more olefinically unsaturated compounds.

High molecular weight linear polymers of carbon monoxide with one or more olefinically unsaturated compounds (for the sake of brevity referred to as A) in which, on the one hand, the monomer units - (CO) - and, on the other hand, the units --A '- derived from the monomers used, can be prepared by the contacting monomers at elevated temperature and pressure with a solution of a palladium-containing catalyst composition in a diluent in which the polymers are insoluble or practically insoluble. During the polymerization, the polymers are obtained in the form of a suspension in the diluent. The above-described polymers have excellent mechanical properties, in particular a very high strength, rigidity and impact resistance. A drawback of the use of the palladium-containing compositions as catalysts is that the palladium largely remains in the polymers and cannot be removed therefrom by washing. The presence of palladium in the polymers is undesirable for two reasons. In the first place, the presence presents problems in the processing of the generally high-melting polymers. This processing, for example by injection molding, must take place in the molten state, the material being at a temperature which is at least 25 ° C above the melting point. Due to the presence of palladium in the polymers, they cannot withstand the high temperatures required for processing. Severe discoloration and decomposition of the polymers takes place. Due to the very strong gelation occurring, the processing of the polymers is greatly complicated. As a rule, the processing problems are greater the more the polymers contain palladium. The presence of palladium in the polymers is furthermore undesirable because it removes palladium from the preparation process. It must be replenished from the outside, which, in view of the price of palladium, can entail very high costs. Especially in those cases where almost all the palladium used ends up in the prepared polymer, this phenomenon can seriously hinder the use of the polymer preparation on a technical scale.

The Applicant has recently conducted an investigation on this subject. It has been found that the palladium content of the polymers can be lowered by expelling the gases still present in the reactor after the polymerization has ended, and subsequently keeping the polymer suspension in the reactor in contact with carbon monoxide at elevated pressure for some time. at a temperature of at least 60 ° C, which temperature is at least 20 ° C higher than that at which the polymerization was carried out. After cooling and releasing the pressure, a polymer with a reduced palladium content can be separated from the polymer suspension thus treated.

The carbon monoxide treatment described above offers the possibility to easily reduce the palladium content of the polymers immediately after the polymerization while they are still in the reactor. However, there is one objection. Namely, it has been found that this purification method is very sensitive to the presence of certain non-noble transition metals. These metals are often added in the form of their salts to the palladium-containing catalyst compositions to enhance their activity. If the polymerization uses a palladium-containing catalyst composition incorporating such salts such as copper salts, no reduction in the palladium content of the polymers will be observed in the subsequent carbon monoxide treatment. Although it has been found that by thoroughly washing the polymers with diluent, the interfering salt can be removed from the polymers, after which the carbon monoxide treatment can still be successfully applied to the polymer suspension, but this requires a number of additional * 880 12.76 - 3 - * process steps. that is, separating the polymers from the slurry, then thoroughly washing the polymers with diluent and finally resuspending the polymers in the diluent.

5 Further research by the Applicant on this subject has now found another way to reduce the palladium content of the polymers. In contrast to the previously described method where the reduction of the palladium content was carried out by chemical means, the currently found way relies on a mechanical separation. The present method takes advantage of the finding that in the present polymers consisting of palladium-containing polymer particles exhibiting a particle size distribution, the smaller particles have a higher palladium content than the larger particles. This finding is highly surprising in view of the fact that the subject polymers are prepared by homogeneous catalysis. It has been found that the palladium content of the polymeric product can be reduced by separating therefrom a palladium-rich by-product fraction which by-product fraction contains the smaller particles.

Furthermore, it has been found that in order to obtain a main product fraction with a significantly reduced palladium content, this by-product fraction should represent at least 10% by weight of the total polymer product.

The present patent application therefore relates to a process for the preparation of polymers in which a mixture of carbon monoxide with one or more olefinically unsaturated compounds is polymerized by contacting the monomer mixture at elevated temperature and pressure with a solution of a palladium-containing catalyst composition in a diluent in which the polymers are insoluble or practically insoluble, and the polymer product thus obtained, which consists of palladium-containing polymer particles exhibiting a particle size distribution, is separated by particle size in a palladium-rich by-product fraction containing the smaller particles. And which by-product fraction makes up at least 10% by weight of the total polymer product and a low-palladium main product fraction containing the larger particles. The patent application further relates to the thus prepared low-palladium main product fraction as well as to molded articles which at least partly consist of this low-palladium main product fraction.

In the process according to the invention a by-product fraction must be separated from the polymeric product, which constitutes at least 10% by weight of the total polymeric product. As the separated by-product fraction constitutes a higher percentage of the total polymer product, the remaining main product fraction will have a lower palladium content. Preferably, the separated by-product fraction constitutes no more than 40% by weight of the total polymeric product, and in particular the amount of by-product fraction separated from the polymeric product is 15-25% by weight thereof.

As set forth above, part 20 of the palladium-containing catalyst composition used in the polymer preparation remains in the prepared polymer. Previous research on the present polymer preparation has shown that this catalyst composition still has activity, whereby further polymerization occurs upon renewed contact of these palladium-containing polymers with the monomer mixture. In this connection, the by-product fraction separated by the process according to the invention can be re-included in the polymerization. This is attractive for two reasons. Firstly, the by-product fraction contains a high palladium content, so that when using it in the polymerization, less fresh catalyst composition need be used. As a result, palladium consumption decreases during polymerization. Furthermore, the by-product fraction consists of the smaller polymer particles which, when exposed to the polymerization conditions again, are given the opportunity to grow into larger polymer particles with a lower palladium content than that from which they originated.

Two cases can be distinguished as to the way in which the product fraction is reintroduced into the polymerization process. If the polymerization is carried out continuously, the by-product fraction may be recycled, in whole or in part, to the polymerization reactor. If the polymerization is carried out batchwise, the by-product fraction can be used in whole or in part in a subsequent batch polymerization.

With regard to the latter embodiment, the following can be noted. Previous research on the present polymer preparation has shown that reactor fouling can be combated by suspending finely divided polymer in the diluent in an amount given by the formula α100xbxc before contacting the monomers with the catalyst solution. where a is the number of grams of the polymer per liter of diluent, b is the number of meters in the average particle size of the

O

Polymer and c represents the number kg / m of the bulk density of the polymer. If it is intended to reintroduce the by-product fraction into a batch polymer preparation, it is preferable to work in such a way that the above requirements are met.

Regarding the separation of the polymeric product into a palladium-poor main product fraction containing the larger particles and a palladium-rich by-product fraction containing the smaller particles, two cases can be distinguished depending on whether the separation is applied to the polymeric product after, for example, by filtration, washing and drying from the slurry is isolated or on the polymer slurry as it leaves the reactor. If it is intended to apply the separation to the polymer as a dry matter, this separation can be effected inter alia by sieving, by fluidization, by pneumatic segregation or by using cyclones. Centrifugation and fluidization are suitable for application of the separation on the polymer slurry "8801276-6". Preferably, use is made for the separation of hydrocyclones with which the polymer suspension can be separated into a suspension containing the by-product fraction and a suspension containing the main product fraction. The availability of the by-product fraction in the form of a slurry in the diluent is advantageous if the intention is to allow the by-product fraction to re-participate in the polymerization either by recirculation in a continuous process or by use in a subsequent batch operation. . As for the work-up of the polymer slurry to a solid product by filtration, washing and drying, this work-up proceeds more easily as the polymer slurry contains fewer small polymer particles. It is therefore advantageous to apply this work-up to a slurry containing only the main product fraction rather than to a slurry containing the entire polymeric product, including the small particles.

By removing the smaller particles from the total polymer product in the method according to the invention, it is not only achieved that the end product has a lower palladium content than the total polymer product, but moreover that the end product is easier to transport and to process. .

The process of the invention uses a paliadium-containing catalyst composition.

Very suitable for the present purpose are catalyst compositions based on a) a palladium compound, b) an anion of an acid with a pKa of less than 6, and c) a diphosphine of the general formula> in which up to or equal various optionally polar substituted hydrocarbon groups and wherein R represents a divalent bridging group containing at least two carbon atoms in the bridge.

. 880 12.76 - 7 ->

The palladium compound used as component a) in the catalyst compositions is preferably a palladium salt of a carboxylic acid and in particular palladium acetate. As component b), an anion of an acid with a pKa of less than 2 (measured in aqueous solution at 18 ° C) is preferably used in the catalyst compositions. More particularly preferred is an anion of a sulfonic acid such as para-toluenesulfonic acid or an anion of a carboxylic acid such as trifluoroacetic acid. In the catalyst compositions, component b) is preferably present in an amount of 0.5 to 50, and in particular 1 to 25 equivalents per mole of palladium. Component b) can be included in the catalyst compositions in the form of an acid and / or in the form of a salt of a non-noble transition metal such as a copper salt.

In the diphosphines of the general formula R-jR2P-R.-PB.3R4 which are suitable for use as component c) in the catalyst compositions, the groups R 1 to R 4 are preferably optionally polar substituted aryl groups and in 20 especially optionally polar substituted phenyl groups.

As polar substituents which can occur in the groups R 1 through R 4, mention may be made, among others, of alkoxy groups such as methoxy groups, dialkylamino groups such as dimethylamino groups and thioalkyl groups such as thiomethyl groups. The catalyst compositions preferably use diphosphines in which the groups R 1 through R 4 are aryl groups, each of which contains one or more polar substituents. Furthermore, preference is given to such diphosphines in which of these polar substituents there is at least one ortho position per aryl group with respect to the phosphorus atom to which the aryl group in question is bonded. Finally, preference is given to diphosphines in which the groups R 1 to R 4 are the same, as well as to diphosphines in which the polar substituents optionally present in the groups R 1 to R 4 are alkoxy groups and in particular methoxy groups. As for the bridge group R present in the diphosphines, preference is given to .8801276-8 groups which contain three atoms in the bridge, of which at least 2 are carbon atoms. Examples of suitable R bridging groups are the -CH2-CH2-CH2 group, the -CH2-C (CH3) 2 "CH2" group and the -CH2-SiCCHg ^ -Cl2 group. Very suitable diphosphines for use as component c) in the catalyst compositions are 1,3-bis (diphenylphosphino) propane, 1,3-bis [di (2-methoxyphenyl) phosphino] propane, 1,3-bis [di (2,4-dimethoxyphenyl) phosphino] propane, 1,3-bis [di (2,6-dimethoxyphenyl) phosphino] propane, and 1,3-bis [di (2,4,6-trimethoxyphenyl) phosphino] propane.

Particular preference is given to the use of catalyst compositions containing as component c) 1,3-bis [di (2-methoxyphenyl) phosphino] propane. In the catalyst compositions, the diphosphines are preferably used in an amount of 0.5-2 and in particular of 0.75-1.5 moles per mole of palladium.

In order to increase the activity of the present catalyst compositions, a 1,4-quinone is preferably incorporated therein as component d). 1,4-benzoquinones and 1,4-naphthoquinones have proved very suitable for this purpose.

The amount of 1,4-quinone used is preferably 10-1000 mol and in particular 25-250 mol per mol palladium.

The polymerization according to the invention is carried out in a diluent in which the polymers are not or practically insoluble. As diluents, both single and composite diluents are eligible. Examples of single diluents are lower aliphatic alcohols such as methanol and ethanol. Examples of formulated diluents are mixtures of lower aliphatic alcohols and lower aliphatic ketones such as mixtures of methanol with acetone or with methyl ethyl ketone. The diluent used in the present polymerization is preferably a lower aliphatic alcohol and in particular methanol.

Suitable olefinically unsaturated compounds which can be polymerized according to the invention with carbon monoxide, 8801276-9, are compounds which consist exclusively of carbon and hydrogen and compounds which contain one or more heteroatoms in addition to carbon and hydrogen. The process according to the invention is preferably used for the preparation of polymers of carbon monoxide with one or more olefinically unsaturated hydrocarbons. Examples of suitable hydrocarbon monomers are ethylene and other alpha olefins such as propylene, butene-1, hexene-1 and octene-1. The process according to the invention is particularly suitable for use in the preparation of copolymers of carbon monoxide with ethylene and for the preparation of terpolymers of carbon monoxide with ethylene and with another olefinically unsaturated hydrocarbon, in particular propylene.

The amount of catalyst composition used in the preparation of the polymers can vary within wide limits. Per mole of the olefinically unsaturated compound to be polymerized, an amount of catalyst is used which preferably contains 0 ~ 10 and in particular 10 ~ 10 -10 ~ mole palladium.

The preparation of the polymers is preferably carried out at a temperature of 40-120 ° C and a pressure of 20-150 bar and in particular at a temperature of 50-100 ° C and a pressure of 30-100 bar. The molar ratio of the olefinically unsaturated compounds to carbon monoxide in the mixture to be polymerized is preferably 10: 1-1: 5 and especially 5: 1-1: 2.

The invention is now illustrated by the following examples.

Example 1 A carbon monoxide / ethylene copolymer was prepared as follows. 80 kg of methanol were placed in a mechanically stirred autoclave with a volume of 150 l. After air was removed from the autoclave by purging with nitrogen, the contents of the autoclave were brought to 55 eC. Ethylene was pressed into the autoclave until a pressure of 15 bar was reached and then carbon monoxide reached a pressure of 45 bar. Then .8801276 -10-

V

placed in the autoclave a catalyst solution containing 120 ml of methanol, 40 ml of toluene, 1.5 mmole of palladium acetate, 30 mmole of trifluoroacetic acid, and 1.8 mmole of 1,3-bis (diphenylphosphino) propane.

During the polymerization, the pressure in the autoclave was maintained at 45 bar by pressing a 1: 1 carbon monoxide / ethylene mixture. After 28 hours, the polymerization was terminated by cooling the reaction mixture to room temperature and releasing the pressure. The polymer was filtered off, washed with methanol and dried at 60 ° C. 5.4 kg of copolymer with a palladium content of 19 gpm was obtained, which means that of the palladium present in the catalyst, 64% remained in the copolymer.

The 5.4 kg copolymer was separated by particle size into nine fractions using eight sieves with decreasing mesh sizes from 250 x 10 m to

C

64 x 10 m. The results are shown in Table I.

Table I

Fraction Mesh Size Weight of Weight of Palladium Content No. of the fraction, the fraction of the fraction, sieve, based on total polymer yield, 10% mg% gdpm 1 250 590 11 9.3 2 180 650 12 14.6 3 150 865 16 17.2 4 125 810 15 19.2 5 105 540 10 18.6 6 90 650 12 21.9 7 75 540 10 22.5 8 64 430 8 25.8 9 325 6 29.8 ”8801 276 - 11 -

According to the invention, if the polymeric product is separated into a by-product fraction comprising fractions 8 and 9 and constituting 14% by weight of the polymeric product and a main product fraction comprising fractions 1-7, this main product fraction has a palladium content of 17, 3 gpm which implies a 9% decrease in palladium content compared to the total polymer product.

According to the invention, if the polymeric product is separated into a by-product fraction comprising fractions 7-9 and constituting 24% by weight of the polymeric product and a main product fraction comprising fractions 1-6, this main product fraction has a palladium content of 16, 9 gpm, which implies a decrease in the palladium content compared to the total polymer product of 11%.

15 Example 2

A carbon monoxide / ethylene / propylene terpolymer was prepared as follows. 70 kg of methanol were placed in a mechanically stirred autoclave with a volume of 150 l. After air was removed from the autoclave by nitrogen purging, the contents of the autoclave were brought to 75 eC. Propylene was pressed into the autoclave until a pressure of 8 bar was reached, then ethylene was reached up to a pressure of 20 bar and finally carbon monoxide was reached until a pressure of 45 bar. A catalyst solution was then introduced into the autoclave consisting of 240 ml of methanol, 80 ml of toluene, 1.5 mmole of palladium acetate, 30 mmole of trifluoroacetic acid, and 30 mmole of 1,3-bis [di (2-methoxyphenyl) phosphino] propane .

During the polymerization, the pressure in the autoclave was maintained at 45 bar by pressing a 1: 1 carbon monoxide / ethylene mixture. After 10 hours, the polymerization was terminated by cooling the reaction mixture to room temperature and releasing the pressure. The polymer was filtered off, washed with methanol and dried at 60 ° C. 5.2 kg t 8801276 was obtained

Jf-12 terpolymer with a palladium content of 16.9 gpm, meaning that of the palladium present in the catalyst, 55% remained in the terpolymer.

The 5.2 kg terpolymer was separated by particle size in six fractions using five sieves with decreasing mesh sizes from 425 x 10 ° m to 90 x 10 ° m. The results are shown in Table II.

Table II

Fraction Mesh Size Weight of Weight of Palladium Content No. of the fraction, the fraction of the fraction, sieve, based on total polymer yield, 10 µg mg gpm 1 425 310 6 12.5 2 355 675 13 13.1 3 250 1870 36 13.7 4 180 365 7 14.1 5 90 520 10 20.5 6 1460 28 23.0

According to the invention, if the polymeric product is separated into a by-product fraction comprising fraction 6 and constituting 28% by weight of the total polymer product and a main product fraction comprising fraction 1-5, this main product fraction has a palladium content of 14.5 ppm which implies a drop in the palladium content relative to the total polymer product of 14%.

Using 1 C-NMR analysis, it was determined that the carbon monoxide / ethylene copolymer prepared according to Example 1 had a linear structure and consisted of units of the formula - (CO 1 -H 2) -.

Also, using C-NMR analysis, it was determined, 8801276 - 13 - *, that the carbon monoxide / ethylene / propylene terpolymer prepared according to Example 2 had a linear structure and that it consisted of units and units - (CO) - (C3H6) ~ which units were randomly distributed in the terpolymer 5.

.8801276

Claims (27)

Process for the preparation of polymers, characterized in that a mixture of carbon monoxide with one or more olefinically unsaturated compounds is polymerized by contacting the monomer mixture at elevated temperature and pressure with a solution of a palladium-containing catalyst composition in a diluent in which the polymers are insoluble or practically insoluble, and the polymer product thus obtained, which consists of palladium-containing polymer particles which exhibit a particle size distribution, is separated by particle size into a palladium-rich by-product fraction containing the smaller particles and which by-product fraction constitutes at least 10% by weight of the total polymer product and a low-palladium main product fraction containing the larger particles. 2. Process according to claim 1, characterized in that the by-product fraction constitutes no more than 40% by weight of the total polymer product. 3. Process according to claim 2, characterized in that the by-product fraction constitutes 15-25% by weight of the total polymer product 20. Process according to one or more of claims 1 to 3, characterized in that the polymerization is carried out continuously and that the by-product fraction is recycled at least in part to the polymerization reactor. Process according to one or more of Claims 1 to 3, characterized in that the polymerization is carried out batchwise and that the by-product fraction is used at least in part in a subsequent batchwise polymer preparation. 6. Process according to claim 5, characterized in that before the monomers are contacted with the catalyst solution in a subsequent batch polymerization, an amount of by-product fraction from a previous polymer preparation is suspended in the diluent, which is amount is given by the formula a> 100 x bxc, where a is the number of grams of the polymer per liter of diluent, b is the number of meters in the average particle size of the polymer, and c is the number 5 kg / n of the bulk density of the polymer. 7. Process according to one or more of claims 1-6, characterized in that the separation of the polymeric product in a main product fraction and a by-product fraction is applied to the polymeric product after it has been separated from the polymer suspension obtained during the polymerization. Process according to one or more of claims 1 to 6, characterized in that the separation of the polymeric product in a main product fraction and a by-product fraction is applied to the polymer suspension obtained during the polymerization. Process according to claim 8, characterized in that the polymer suspension obtained during the polymerization is separated using two hydrocyclones into two suspensions, one of which contains the main product fraction and the other the by-product fraction. 20 10. Process according to one or more of claims 1-9, characterized in that a catalyst composition is used based on a) a palladium compound, b) an anion of an acid with a pKa of less than 6, and c) a diphosphine of the general formula R 1 -R 2 P-R-PR 3 R 4 wherein up to R 1 represents equal or different optionally polar substituted hydrocarbon groups and wherein R represents a divalent bridging group containing at least two carbon atoms in the bridge. Process according to claim 10, characterized in that a catalyst composition is used which is based on a palladium salt of a carboxylic acid such as palladium acetate as component a) and an anion of an acid with a pKa of less than 2 as component b). 12. Process according to claim 10 or 11, characterized in that a catalyst composition is used which is based on an anion of a sulfonic acid such as para-toluenesulfonic acid or of a carboxylic acid such as trifluoroacetic acid as component b. ) and that component b) is present in the catalyst composition in an amount of 1 to 25 equivalents per 5 moles of palladium, 13. Process according to one or more of claims 10-12, characterized in that a catalyst composition is used in which component b) is incorporated in the form of an acid or in the form of a salt of a non-noble transition metal 10 such as a copper salt. Process according to one or more of claims 10-13, characterized in that a catalyst composition is used in which component c) is present in an amount of 0.75-1.5 mol per mol palladium. Process according to one or more of claims 10-14, characterized in that a catalyst composition is used in which the groups present in component c) are optionally polar substituted aryl groups such as phenyl groups. 20 A process according to claim 15, characterized in that a catalyst composition is used in which the groups R 1 - 1 to R 1 - aryl groups present in component c) each contain one or more polar substituents, of which at least one aryl group contains one is ortho-oriented to the phosphorus atom to which the aryl group in question is bonded. 17. Process according to claim 16, characterized in that a catalyst composition is used in which the groups R 1 through R 1 present in component c) are mutually identical and contain, as polar groups, alkoxy groups such as methoxy groups. 18. Process according to one or more of claims 10-17, characterized in that a catalyst composition is used in which the divalent bridge group R present in component c) contains three atoms in the bridge, at least two of which are carbon atoms. Process according to one or more of claims 10-18, characterized by using a catalyst composition based on 1,3-bis [di (2-methoxyphenyl) phosphino] propane as component c ). 20. Process according to one or more of claims 10-19, characterized in that a catalyst composition is used in which a 1,4-quinone additionally occurs as component d). 21. Process according to claim 20, characterized in that a catalyst composition is used in which as component d) 1,4-benzoquinone or 1,4-naphthoquinone is present in an amount of 25-250 moles per mole palladium. Process according to one or more of claims 1-21, characterized in that the polymerization is carried out in a lower aliphatic alcohol such as methanol as a diluent. Process according to one or more of claims 1-22, characterized in that the olefinically unsaturated compounds used are hydrocarbons such as ethylene or a mixture of ethylene with another olefinically unsaturated hydrocarbon such as propylene. 24. Process according to one or more of claims 1-23, characterized in that it is carried out at a temperature of 50-100 eC, a pressure of 30-100 bar and a molar ratio of the olefinically unsaturated compounds to carbon monoxide in the mixture to be polymerized of 5: 1-1: 2 and that per 25 moles of olefinically unsaturated compound to be polymerized, an amount of catalyst composition is used which contains 10 to 10 mol of palladium. 25. Process for preparing polymers of reduced palladium content according to claim 1, substantially as described above and in particular with reference to the examples. Polymers with reduced palladium content prepared according to one or more of claims 1-25. 27. Shaped articles which at least partly consist of polymers according to claim 26. 8801276