CH647535A5 - PROCESS FOR THE COPOLYMERIZATION OF ETHYLENE WITH MULTI-UNSATURATED HYDROCARBONS. - Google Patents

Description

The present invention relates to an improved process for the preparation in high yield of copolymers starting from ethylene, alone or in mixture with one or more alpha-ole-end compounds, and a compound containing two or more olefinic unsaturations, optionally conjugate, the process being characterized in that a catalytic system consisting of i) an organometallic compound of the III group of the periodic system and ii) a compound obtained by reaction of metallic magnesium or metallic manganese vapors with a titanium compound and a halogen donor.

In the case of products deriving from the copolymerization of ethylene only with the pluri-unsaturated compound, crystalline copolymers are obtained.

The applicant is aware of the existence of various processes for obtaining crystalline copolymers deriving from the polymerization of ethylene with a conjugated or unconjugated multiolefin, and in particular butadiene and ethyl-den-norbornene (see e.g. patent. Swiss No. 621 355, patent No. 606 148, patent No. 628 909). These processes are based on coordinated vanadium-based anionic catalysts which, while providing high polymerization yields, do not reach levels of catalytic activity which allow to avoid the onerous purification of the copolymer from the transition metal residues, harmful for the oxidative stability of the copolymer and for the color they generate. In addition, the request5

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dente became aware of a patent no. 628 597 which refers to a catalytic composition extremely active in the polymerization and copolymerization of the mono alpha olefins obtained by reaction of an organometallic compound of the III group of the periodic system with a composition obtained for i) vaporization or sublimation in vacuum of magnesium and ii) condensation of these vapors in a condensed phase comprising a titanium halide tetra and a halogen donor.

In the same patent application it is shown that the activity of the catalytic composition in the homo and copolymerization of the a-olefins is extremely high when the quantity of vaporized metallic magnesium is such as to obtain an atomic ratio Mg / Ti much higher than 0.5 in the phase condensed and in it there is a compound capable of yielding halogen to metallic magnesium which exceeds the atomic ratio Mg / Ti by 0.5 corresponding to the MgX2 complex. . 2TiX3 (X = halogen). In this way there is further formation of MgX2 which interacts with the stoichiometric complex giving rise to a new and more active complex containing Titanium.

We have now found that by suitably modifying the vaporization conditions of magnesium, and choosing

The reactants and the reaction conditions, it is possible to carry out the copolymerization of ethylene, alone or in mixture with other alpha-olefins, with a compound containing one or more olefinic unsaturations to give, in the case of the use of ethylene only, highly polymers crystalline; next to magnesium, it can be used, to obtain the catalytic composition,

manganese.

The activity of the catalytic system described above is such as to produce an amount of copolymer per g titanium equal to or greater than 50 kg. The catalytic composition is obtained by vaporizing the magnesium or manganese in a metallic state or an alloy thereof and condensing the vapors in a cold solution obtained by dissolving a titanium compound and an alloyed compound in an inert diluent.

Metal M can be used both in powder and in grains or in solid wood and is preferably vaporized under vacuum by sublimation.

In the case of magnesium, for a pressure between

2 and IO-4 torr, the temperature varies, depending on the former, from about 650 to 300 ° C.

Mangenese needs more demanding conditions: 800-1100 ° C for IO "1 -5- IO-4 torr.

Operating at higher temperatures, the metal can vaporize from the molten state even at ambient pressure.

The solution in which the vapors are condensed is kept under stirring and kept at a low temperature: in relation to the solvent used, this can be fixed in the range from -120 to 0 ° C, generally between -80 and -20 ° C . The use of an inert diluent, chosen among the low volatility and low freezing temperature hydrocarbon solvents (e.g. n-heptane, n-octane, toluene, etc.), is not strictly necessary since the reaction can also be carried out within titanium compound and pure halogenated compound.

Among the liquid titanium compounds suitable for the purpose there is titanium tetrachloride while among the halogen compounds there are alkyl halides, whose measured excess can constitute the reaction medium.

Examples of alkyl halides that can be used consist of I-chloro-butane, 1-chlorohexane, 1-bromo-hexane, but the secondary or tertiary alkyl halides and the aryl or alkylaryl halides are also reactive.

Among the inorganic halides the most suitable have proved to be SnCl4, SbCl5, GeCl4, POCl3.

Among the titanium compounds, in addition to tetrachloride, other trivalent halides, alcohols, halogen alcohols, chelates and all organometallic derivatives are also effectively used; in practice any titanium compound s can be used differing from each other only for the speed of reaction.

The M / Ti ratio to be obtained in order to obtain extremely active catalytic compositions is greater than 0.5 and particularly> 4.

The preferred value for said ratio is between 15 and 30, a further excess of M (Mg or Mn) not constituting an advantage.

The quantity of the halogen donor compound present in the reaction is regulated on the quantity of M, with respect to 15 which is in ratio> 2 in the case of monohalogenated organic compounds, and in ratio> 1 in the case of inorganic compounds capable of releasing more than one halogen atom per molecule. The reaction between the vapors of M, the Ti compound and the halogenated compound occurs in part already at the low temperatures previously indicated; for its completion it is necessary either a long time (some days) of tempering at room temperature or, preferably, a heat treatment of a few hours (1-5), in relation to the chosen temperature (50-180 ° C). The reaction is faster when the halogen donor is inorganic in nature.

The halogen donor is not strictly required in the solution in which the metal vapors are condensed and kept at a low temperature; it can be added later, and in any case before the solution is brought to a higher temperature for the completion of the reaction.

The fine suspension, obtained as described above, is usually used directly as a catalytic component for the polymerization above, since neither any excess of one of the reactants nor any secondary reaction products are substantially disturbing agents for the formation of the catalyst.

Alternatively, said suspension can be filtered and the solid resuspended in the dispersant deemed most suitable, 40 generally the same in which the polymerization is carried out. Or, again, the solid compound can be dispersed on an inert solid support constituted, for example, by the same polymer that is to be produced.

The other catalytic component is constituted, as already said 45, by an organometallic compound of an element of the III group of the periodic system.

Of these elements, aluminum is the most used for efficiency and convenience reasons.

Examples of the compounds used are: the trialkyl- and triaryl-sllu-50 minium, such as Al (C2H5) 3, rAl (i-C3H7) 3, rAl (C6H5) 3, the alkylaluminium hydrants, such as Al ( H) (i-C3H7) 2, the alkyl- and aryl-aluminum halides, such as Al (C, H5) 2Cl and Al (C2H5) Cl2.

Trialkyl derivatives are preferred, however their mixtures with halogenated derivatives are also very effective. 55 The molar ratio between the organometallic compound (s) and the titanium compound for maximum specific activity to be reached must be greater than 3.

In view of the fact that extremely small quantities of the 60 titanium compound are used in polymerization, the aforesaid ratio is, for practical reasons, kept very high, for example between 100 and 500.

As already mentioned above, the copolymerization process object of the present invention is based on the copolymerization of ethylene with a conjugated or non-conjugated multiolefin and is characterized by the use of the catalytic components described above in the presence of an inert diluent, at temperatures between 40 and 120 ° C and with operating pressures between 1 and 20 kg / cm2.

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In tests carried out discontinuously, the introduction of reactants into the reactor is carried out so that the catalyst is formed in the presence or in contact with the mixture of the two monomers.

In practice there are two ways of operating, both effective: in the first, the catalytic component containing the titanium is introduced last, in the second the reaction between the catalytic components is carried out separately and subsequently added to the monomeric mixture; in the latter case there is a pre-contact time which, although not critical, is preferable not to be very prolonged, in particular when using another Al / Ti ratio.

Among the inert diluents aliphatic hydrocarbons are those preferably used.

The presence of a diluent is not, however, strictly necessary in the polymerization phase since it is possible to operate in the gaseous state, introducing the catalyst dispersed in a little low-boiling solvent.

The monomers that the applicant has chosen to exemplify the copolymerization process are those listed below. Of course, the conditions detailed above are absolutely general and ethylene copolymers of any type can be prepared by applying the technique referred to in this application, on the basis of the detailed teachings for the copolymers listed below, without leaving the context: it will be the task of the expert from the branch choose the most suitable operating conditions in relation to the desired polymer.

The monomers are: ethylene on one side and a cyclic hydrocarbon on the other. Prototypes of these classes of hydrocarbons, preferred for their reactivity and for their low cost, are 1, 3-butadiene and 5-ethyliden- (2,2, 1) -bicicIoepta-2-ene (ethylidennorbornene).

They have a polymerization reactivity lower than that of ethylene for which they are fed in excess (50 times or more) with respect to the quantity of the same monomer which is desired to have in the copolymer.

This excess is used by recycling the solution. The amount of ethylene comonomer present in the co-polymer useful for practical purposes is a few percentage units (less than 10% by moles).

The regulation of the molecular weight of the copolymer can be made by introducing hydrogen, as well as by varying the reaction conditions. The copolymers obtained by the process object of the present invention have properties which vary with the composition. The ethylene-buta-diene copolymers contain trans-type unsaturations while eis and vinyl-type unsaturations are absent or almost absent, testifying to a 1,4 trans addition of the butadiene units.

Ethylene-butadiene copolymers rich in ethylene are characterized by density values between 0.940 and 0.960, by melting temperatures around 130 ° C and by a distribution of unsaturations as shown by the attached 13C-NMR spectrum (relating to a copolymer having 12.3% by moles butadiene), in which three peaks attributable to butadiene units differently structured along the polymer chain are observed (peaks attributable to butadiene methylenes a: a = 32.6; b = 32.7 and c = 32.9 ppm). It should be noted that analogous copolymers obtained according to the cited art show only two of said three peaks in the 13C-NMR spectrum. It is known that crystalline poly-alpha-olefins such as polyethylene, isotactic polypropylene, isotactic polybutene, etc. have been on the market for some time.

These polyalphaolefins are constituted either by homo-polymers or by copolymers with small quantities of a second alpha-olefin to solve some technological problems.

The quantity of the second olefin is normally so low as not to excessively decrease the crystallinity with respect to the homopolymer, since some important mechanical characteristics are associated with the high crystallinity such as modulus, breaking load etc.

In the copolymers of ethylene with butadiene the compatibility in the same crystal of units of the two types allows to obtain substantially crystalline polymers in the whole range of compositions from pure polyethylene to pure trans polybutadiene.

There is therefore in this case the limitation existing in the case of the copolymers of the mono alpha olefins in which an olefin must be contained in a very low quantity in the co-polymer to keep the crystallinity high.

An extremely important advantage of the copolymers obtained according to the process covered by this patent is linked to the fact of containing unsaturations (or in the main chain, as in the case of butadiene or in the lateral groups, as in the case of ethylidennorbornene).

By means of these unsaturations, the copolymer can be easily crosslinked (with sulfur or other reagents) further improving its technological characteristics such as thermal resistance, impact resistance or resistance to agents that induce the formation of cracks (environmental stess cracking).

The unsaturations also allow some otherwise difficult if not impossible transformations such as foaming and thermoforming of plates.

Example 1

The preparation of the catalytic component containing titanium is carried out in a 1 1 rolling glass flask, arranged horizontally, in the center of which an electrically heated alumina crucible is placed by means of tungsten filament.

240 ml of n-heptane and 0.2 ml of TiCl4 are loaded into the flask; 0.9 g of magnesium shavings are loaded into the crucible.

The solution is cooled to -70 ° C.

After having practiced the vacuum in the apparatus (IO-3 torr) placed in rotation, the crucible is heated by applying an electric voltage to the ends of the filament which is able to heat it.

The vaporization of Mg causes the formation of a brown suspension to which, after voiding the void by introducing nitrogen, n-butyl chloride (1-chlorobutane, 8.2 ml) is added.

The suspension will then be heated with reflux refrigerant for 3 hours at 80 ° C.

Copolymerization

In a stainless steel autoclave with a capacity of 5 1, equipped with mechanical stirring and electric thermoregulation, vacuum is practiced, then a solution prepared by suction is introduced with:

anhydrous n-heptane I 2200

butadiene g 200

A1 (C2H5) 3 mmoles 15

The autoclave is thermostated at 70 ° C before introducing hydrogen and ethylene at partial pressures of 3.5 and 4.5 kg / cm2, respectively.

10 ml of the heptane suspension obtained as described above and containing 0.075 mmol of titanium is introduced into the autoclave, with ethylene overpressure, with a 100 ml capacity steel vial and provided with an inlet valve and a discharge valve.

Finally it is added to the mixture already present in the aid

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in the first 5 minutes of reaction, an hepatic solution (50 ml) of AI (C2H5) C12 (7.5 mmoles) is touched by means of a piston pump.

An absorption of ethylene is immediately observed, which is fed continuously in order to keep the initial pressure constant at a temperature of 70 ° C.

After three hours it is found that ethylene is still absorbed with an intensity approximately equal to the initial one.

The test is however interrupted by draining and filtering the suspension contained in the autoclave: 388 g of dry polymer are obtained having an MFI2.16 of 49.5, a content of butadiene units (moles) of 3.3% and a melting temperature (Tm), determined by differential thermal analysis, of 131 ° C.

The polymer, which has the appearance of a white solid quite similar to that of a polyethylene, is mixed with the following compounds (g per 100 g of polymer):

Zinc oxide

5

Stearic acid

1

2,2'-methylene-bis (4-methyl-phenol)

(A.O. 2246)

1

N-ossidietilbenzotiazolo-2-sulphenamide

(NOBS special)

1.5

dibenzothiazyl disulfide (Vulkacit DM)

0.5

Sulfur

3

The mixture is treated in a press at 180 ° for 30 minutes, obtaining a product having 40% residues when extracted with boiling xylols (the polymer as such is completely soluble).

Example 2

In the autoclave and with the methods described in example 1, a test is carried out at 85 ° C.

The partial pressures of ethylene and hydrogen are, in this case of 5 and 3 kg / cm2, respectively, while the introduced butadiene is 250 g.

All other quantities as in example 1.

After 3 hours of polymerization, 250 g of dry copolymer are obtained having the following characteristics: butadiene units = 3.3% (moles), MFI216 = 0.84, MFI216 / MFI216 = 32.5, melting temperature = 129 ° C, resistance impact = 13.7 kg / cm2.

Subjected to cross-linking as described in Example 1, the product obtained shows an impact resistance of 50.4 kg / cm3.

Example 3

Using the same equipment and the same modalities of the previous examples, a polymerization test is carried out using the following reagents:

n-heptane ml

1840

butadiene g

102

A1 (C2H5) 3

mmol

17.6

h2

kg / cm2

3.5

ethylene kg / cm2

5.0

Ti complex (see ex. 1)

mmol

0.06

The autoclave is kept at 85 ° C both during the introduction of the gases and during the polymerization, during which the consumed ethylene is replenished.

After four hours the test is stopped by filtering and drying the product obtained: 285 g.

The analyzes provided the following results: butadiene units% = 1.5 (moles), MFI216 = 0.99 g / 10, MFI216 = 27.4, Tm (DSC) = 133 ° C.

Example 4

In a stainless steel autoclave of the type described in Example 1 but with a capacity of 2 1, a solution prepared from:

n-heptane I 400

bicycle (2,2, l) -5-ethyliden-2-

-eptene (ethylidennorbornene) 40 ml

The autoclave is thermostated at 85 ° C and ethylene and hydrogen are introduced at partial pressures of 5 and 3 kg / cm2, respectively.

The catalyst consisting of the heptanic suspension of the interaction product for 60 min is introduced by means of a steel vial with N2 overpressure. at room temperature between 5 mmoles of Al (i-C4H9) 3 and 0.012 mmoles of titanium in the form described in example 1.

The test lasts 1 hour during which the consumed ethylene is replenished in order to keep its partial pressure constant.

The solid product obtained by filtration of the drying suspension weight 35 g.

It has the following characteristics. 3.3% ethylidennorbornene (weight), MFI216 = 3.4 g / 10 ', MFI21i6 = 33, 820' = 0.9633 g / cm3.

Example 5

The titanium-containing catalytic component is prepared in a similar way to that described in Example 1, but starting from the following reagents:

l-chlorooctane 120 ml

TiCl4 0.088 ml

Metallic manganese 1.5 g

By cooling the solution to -50 ° and applying a vacuum of IO-4 torr, the manganese is vaporized and condensed: a dense dark brown suspension is obtained, which is then brought to 100 ° C for one hour.

Chemical analysis shows that the homogenized suspension contains: Ti 5.10 mmol / I, Mn 186.2 mmol / 1, Cl 390.0 mmol / 1.

Copolymerization

A copolymerization test between butadiene and ethylene is carried out in the same apparatus described in example 1.

The solution introduced into the reactor is obtained starting from:

n-heptane 2200 ml butadiene 250 g

AI (i.C4H9) 3 22.5 mmoles

After thermostating at 85 ° C, the autoclave is pressurized with 3 kg / cm2 of hydrogen and 5 kg / cm2 of ethylene.

Finally, 15 cm3 of the suspension containing the titanium complex obtained as described above are introduced. For three hours more ethylene is added, in order to maintain the initial pressure which is 10 kg / cm2 at 85 ° C, then the test is stopped and the product filtered and dried. 200 g of polymer are obtained having the following characteristics: butadiene units 1.4 trans 5.15% (moles), MFI2, i6 = 0.05 g / 10 ', Tm (DSC) = 132 ° C, [yj] ( in decalin at 105 °) 1.75.

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Example 6

The preparation of the titanium-containing catalytic component takes place, in an apparatus similar to that described in Example 1, starting from:

cantato is titanium-free, while the homogenised suspension contains: Ti 6.32 mmol / 1, Mg 187 mmol / 1, Sn 207 mmol / 1, CI 863 mmol / 1.

n-octane

TiCl4

SnCl4;

Metallic Mg

300 ml 0.187 ml 8 ml 1.2 g

Magnesium is vaporized at 5, IO2-torr and condensed in the solution kept at about - 50 ° C.

The suspension obtained is brought to room temperature. After 24 hours, the solution above the solid de-

Copolymerization The test is carried out in the autoclave described in Example 1, at 85 ° C, using the same methods and the same reagents as in Example 5, apart from the titanium-containing catalytic component which this time consists of 11, 85 ml of the above suspension. The polymer obtained weighs 180 g and shows the following properties: MFI2j16 = 0.1 g / 10 '; Tm = 131 ° C (DSC); butadiene units = 3.34 mol%.

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1 sheet of drawings

Claims (26)

647535 1. Process for the copolymerization in high yield of ethylene alone or in union with one or more alpha-olefins with a multiolefin containing unsaturations, possibly also conjugated, consisting in bringing ethylene and multi-olefin in contact with a catalytic system consisting of (a) a composition obtained by reaction of metallic magnesium or metallic manganese vapors, a titanium compound and a halogen donor and (b) an organometallic aluminum compound. 2. Process according to claim 1, characterized in that the component (a) of the catalytic system is obtained by vaporizing the magnesium or manganese or an alloy thereof, therefore condensing the vapors in a diluent containing the titanium compound, and optionally, the halogen donor. 2 Process according to claim 1, characterized in that the component (a) of the catalytic system is prepared by sublimation of the magnesium under vacuum, with depressions varying from 2.66 to 1.33. IO-4 mb and at temperatures between 300 ° C and 650 ° C. Process according to claim 1, characterized in that the component (a) of the catalytic system is prepared by sublimation of the manganese under vacuum at depressions ranging from 0.133 to 1.33. IO-4 mb at temperatures between 800 ° C and 1100 ° C. 5. Process according to claim 1, characterized in that the component (a) of the catalytic system is prepared by condensing the metal vapors in an inert solvent chosen from among the halitatic or aromatic hydrocarbons and kept at a temperature between -120 ° C and 0 ° C. 6. Process according to claim 5, characterized in that the preparation reaction of the component (a) of the catalytic system is completed at a temperature comprised between 20 ° C and 180 ° C. 7. Process according to claim 1, characterized in that the catalytic system is constituted in such a way that the titanium compound is selected from the halides, alcohols, halogen alcohols and organometallic derivatives of trivalent and tetravalent titanium. 8. Process according to claim 1, characterized in that the halogen donor is selected from the organic or inorganic halides. 9. Process according to claim 1, characterized in that the organic halogen donor compound is selected from chloroalkanes, bromoalkanes, chloroarens and bromoarenes. 10. Process according to claim 1, characterized in that the molar ratio between the organic halogen donor compound and the vaporized metal is equal to or greater than two. 11. Process according to claim 8, characterized in that the inorganic halogen donor compound is selected from SnCl4, SbCl4, GeCl4 and POCl3. 12. Process according to claim 11, characterized in that the molar ratio between the inorganic halogen donor compound and the vaporized metal is equal to or greater than 1. Process according to claim 1, characterized in that the component (a) of the catalytic system is obtained by reacting the vaporized metal and the titanium compound with M / Ti ratios equal to or greater than 4, preferably between 15 and 30 . 14. Process according to claim 1, characterized in that ethylene is copolymerized with a multiolefin containing also conjugated unsaturations. 15. Process according to claim 14, characterized in that said copolymerization reaction is carried out in the presence of an inert solvent. 16. Process according to claim 15, characterized in that the inert solvent is the same used for the preparation of the component (a) of the catalytic composition. 17. Process according to claim 14, characterized in that said copolymerization reaction is carried out at a temperature comprised between 40 ° C and 120 ° C. 18. Process according to claim 14, characterized in that the polymerization reaction is carried out at a pressure comprised between 1.02 and 20.4 bar. 19. Process according to claim 14, characterized in that ethylene and multilolefin are fed to the catalytic system in the gaseous state and in the absence of solvents. 20. Process according to claim 14, characterized in that the reaction is carried out by placing the catalytic composition on an inert support. 21. Process according to claim 1, characterized in that the reaction is carried out at a pressure of between 1.02 and 30.6 bar. 22. Process according to claim 1, characterized in that the reaction is carried out at a temperature comprised between the ambient temperature and a temperature not higher than the melting temperature of the copolymer. 23. Process according to claim 14, characterized in that 1,3-butadiene is used as multiolefin. 24. Process according to claim 14, characterized in that ethylidennorborene [5-ethylidene (2,2, 1) bicyclohepta-2-ene) is used as the multiolefin. 25. Crystalline copolymers of ethylene with a multiolefin containing also conjugated unsaturations, prepared by the process according to claim 1, characterized by the presence of reactive unsaturations in the linear macromolecule. 26. Ethylene-butadiene copolymer prepared by the process according to claim 1, characterized in that it has a 13C-NMR spectrum having three peaks at 32.6 - 32.7 and 32.9 ppm characteristic of the methylene groups of the butadiene units .