CS257260B2 - Production method of homopolymere ethylene or copolymere ethylene with at least one alfa oefine - Google Patents

Abstract

A process for producing a homopolymer of ethylene or ethylene copolymers with at least one C 3 -C 4 α-olefin by gas phase polymerization at 10 to 115 ° C using a catalyst system comprising A) a precursor supported on a carrier consisting of 1) vanadium compound which is the reaction product of a vanadium halide, wherein the halogen is chlorine, bromine or iodine and an electron donor, which is a liquid organic Lewis base in which the aldehyde halide is soluble, 2) the MXa modifier, where M is boron or the radical AlR (3a), wherein R is independently of one another with the proviso that the total number of aliphatic carbon atoms in any R group is not greater than 14, X is chlar, bromo or iodo and a is 0, 1 or 2 with the proviso that when M is boron denotes 3 and 3) a solid inert support comprising silica or alumina, on which the vanadium compound and the modifier are r applied. B) AIR3 cocatalyst, wherein R is as defined above, and C) R c is CX (4-b), wherein R 'is hydrogen or unsubstituted or halogenated alkyl having up to 6 carbon atoms, X' is halogen and b is 0, 1, or 2.

Description

The present invention relates to a process for the production of an ethylene homopolymer or an ethylene copolymer with at least one C 3 -C 10 alpha-olefin using a modified vanadium catalyst. The polymers obtained have a desirable property profile suitable for certain applications.

Polyethylenes of relatively broad molecular weight distribution have extensive application in the field of wire and cable insulation and can be used for blow molding and tube production. Such wide molecular weight polyethylenes, made, for example, by the method disclosed in U.S. Patent No. 3,324,095 to Carrick et al., Are unstable due to the relatively high level of unsaturation. Polyethylenes with a relatively narrow molecular weight distribution can be produced in the gas phase as described, for example, in US Patent No. 4,302,565 to Gocke et al. And US Patent No. 4,302,566 to Karol et al. Such gas phase polymerization methods use high activity catalysts to obtain low unsaturation polyethylenes that have high utility in various film applications. However, such polyethylenes have limited applicability in other areas where higher melt flow and extrusion options are required, and lower melt refraction for polyethylene with a wide molecular weight distribution. It would therefore be desirable to develop a highly active catalytic system and process for producing highly saturated vapor phase polyethylene having a wide molecular weight distribution.

Vanadium catalysts are used to produce polyethylenes. U.S. Pat. No. 3,956,255 (Ort) discloses an ethylene polymerization catalyst system essentially consisting of a vanadium compound that has reacted with an alkyl aluminum alkoxide and a trialkyl aluminum. This catalyst system is deposited on silica which has been reacted beforehand with an alkyl aluminum or alkylaluminum alkoxide. A halogenated alkane may optionally be used as the promoter.

U.S. Patent No. 4,173,698 to Kanoh et al. Discloses an ethylene polymerization catalyst which is a vanadium chloride-ether complex compound combined with an aluminum halide. The product is not coated. An organoaluminum compound is used as the cocatalyst.

U.S. Patent No. 4,202,958 (Yamaguchi et al.) Relates to a process for the polymerization of ethylene using a non-carrier solid catalyst obtained by reducing a vanadium halide with an organoaluminum compound in the presence of an ether compound. Here again, an organoaluminium cocatalyst is used.

U.S. Patent 4,263,171 (Shida et al.) Is a representative publication relating to catalysts for olefin polymerization using magnesium-containing compounds. The patent discloses a silica supported catalyst consisting of a magnesium-aluminum complex with a halogenated transition metal compound (including vanadium).

U.S. Patent No. 4,294,947 to Doerk et al. Describes the copolymerization of ethylene with 1-butene in liquid 1-butene as a solvent using a non-carrier catalyst comprising a reaction product of vanadyl chloride and / or -alkoxide with alkylaluminium chloride and organoaluminum cocatalysts.

Many of these publications, representing the prior art, are directed to obtaining a catalyst with high activity or to selectively improve individual polymerization methods or polyethylene properties. Because of the complexity, it was not possible to obtain an industrially suitable optimized gas phase process using the vanadium catalyst for the production of polyethylenes with the desired balance of properties prior to the present invention. To achieve this, the catalyst must provide a better hydrogen response in order to achieve a very low level of polyethylene unsaturation.

Furthermore, it must exhibit a high degree of productivity so that the catalyst residue in the polyethylene is so small, preferably less than 10 ppm of vanadium, that this would allow it to remain in the catalyst and to eliminate the catalyst removal step. The catalyst must furthermore provide polyethylene which is easily formed by various molding processes, i.e. polyethylene having a relatively broad molecular weight distribution and a wide range of melt index. The catalyst must also allow increased copolymerization of ethylene with other alpha-olefins in order to control the density of the polyethylene over a wide range and to expand the range of useful comonomers. The polyethylene obtained using such a catalyst is intended to have a high bulk density so that handling and shipping costs are commercially acceptable. The particles of the polyethylene obtained must be sized so that they can be easily suspended in a fluidized bed reactor and have a low dust content. The resulting polyethylene should be in the form of bulk particles and should not contain agglomerates such as sintered particles or lumps. All these criteria must be met simultaneously by the catalyst and at the same time the catalyst system should be as simple as possible. Catalyst systems with a minimum number of components are preferred.

SUMMARY OF THE INVENTION The present invention provides a process for the production of an ethylene homopolymer or an ethylene copolymer with at least one C 3 -C 10 alpha-olefin by gas-phase polymerization using a modified vanadium catalyst, characterized in that the monomer or mixture is present at 10 to 115 ° C. in contact with a catalyst system comprising

(A) a precursor deposited on a carrier consisting essentially of:

(1) the vanadium compound which is the reaction product;

(a) vanadium halide, wherein the halogen is chlorine, bromine or iodine; and

(b) an electron donor, which is a liquid organic Lewis base in which vanadium halide is soluble;

2) a modifier of formula I

MX _and (I) where

M is boron or a radical ^ ₃ _ All _a) in which R are each independently alkyl with the proviso that the total number of aliphatic carbon atoms in any group R is not greater than 14,

X is chlorine, bromine or iodine and a is 0, 1 or 2 with the proviso that when M is boron, a is 3 and

(3) a solid inert carrier, consisting of silica or alumina, on which the vanadium compound and modifier are applied;

B) a cocatalyst of formula II air ₃ wherein

R is as defined above and

C) a promoter of formula III

R, CX, _IIIb (4-b) (II) (III) wherein

R 'is hydrogen or unsubstituted or halogenated alkyl having up to 6 carbon atoms

X 'is halogen and b is 0, 1 or 2.

The polyethylenes thus produced have a better balance of flow properties, molecular weight distribution, bulk density and saturation. Their density and melt index can be selected within a wide range.

The polyethylene produced by the process of the present invention is an ethylene homopolymer or copolymer of a predominant molar proportion, i.e. at least about 50%, of ethylene and a minor molar proportion, i.e. less than about 50%, of one or more C 3 -C 10 alpha-olefins. Preferred alpha-olefins are propylene, 1-butene, 1-hexene, 4-methyl-1-pentene and 1-octene. Other monomers may be used including conjugated or unconjugated diene such as butadiene, 1,4-hexadiene and ethylidennorbornene.

The polyethylenes prepared by the process of the invention have suitably balanced properties. Their density may range from about 860 to 960 kg.m. They may have a melt index from a non-flow rate of up to about 300 g / 10 min, preferably from about 0.1 to about 50 g / 10 min. They have a broad molecular weight distribution, which is defined by the ratio of the weight average molecular weight to the number average molecular weight (Μ / M), higher w n than about 10, preferably in the range of 14 to 22. They also have a high bulk density.

-3 -3 at least about 320 kg.m, preferably in the range of about 384 to about 512 kg.m. Their level of unsaturation is very low and is less than 1 carbon-carbon double bond per thousand carbon atoms (C = C / 1000 C), preferably less than about 0.2 C = C / 1000 C and particularly preferably less than The copolymers have a residual catalyst content of less than about 10 ppm, preferably less than 6 ppm, expressed in parts of vanadium metal per million parts of copolymer. Preferred polymers produced by the gas phase process of the present invention are in the form of bulk solids that are substantially free of agglomerates in the form of sintered particles or lumps.

The polyethylenes of the present invention are suitable for a wide range of applications including blow molding, foil and tube making, coating extrusion, as well as wire and cable applications.

The catalyst system of the present invention consists of a supported precursor, a cocatalyst and a promoter. The precursor coated on the carrier consists essentially of a vanadium compound and a modifier impregnated on a solid inert carrier. The vanadium compound in the precursor is a reaction product formed from vanadium halide and an electron donor. The halogen in the vanadium halide is chlorine, bromine, or iodine, or mixtures thereof. A particularly preferred vanadium halide is vanadium trichloride of formula VCl2.

The electron donor is a liquid organic Lewis base in which vanadium halide is soluble. The electron donor is selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic esters, aliphatic ketones, aliphatic amines, aliphatic alcohols, alkyl and acycloalkyl ethers, and mixtures thereof. Preferred electron donors are alkyl ethers and cycloalkyl ethers, especially tetrahydrofuran. Each molar vanadium moiety is in the form of a complex with about 1 to about 20, preferably about 1 to about 10, and particularly preferably about 3 molar electron donors.

As the modifier of formula (I), alkyl-aluminum mono- and dichlorides having 1 to 6 carbon atoms in the alkyl group or boron trichloride are preferably used in the supported precursor. Diethylaluminum chloride is particularly preferred. About 0.1 to about 10, preferably about 0.2 to about 2.5, parts of a molar modifier per part of a molar electron donor are used.

The carrier is a solid, porous particulate material that is inert to polymerization.

The carrier consists essentially of silica or alumina, i.e. silica or alumina or mixtures thereof. If desired, the carrier may contain other substances, such as zirconium or thorium dioxide or other compounds that are chemically inert to the polymerization, or mixtures thereof.

The carrier is used in the form of a dry powder having an average particle size of between about 10 and about 250, preferably between about 20 and about 200, and particularly preferably between about 30 and about 100 microns.

2-1 ~ 2 -1

The porous support has a specific surface area of at least about 3 mg and preferably at least about 50 mg. A preferred carrier is silica having a pore size of at least about 8 nm, preferably at least 10 nm. The carrier is pre-dried by heating to remove water, preferably to a temperature of at least about 600 ° C.

The amount of carrier used is selected to provide a vanadium content of about 0.05 to about 0.5 mmol vanadium per gram (mmol V / g) and preferably between 0.2 to about 0.35 mmol V / g, particularly preferably about 0.25 mmol V / g.

Prior to the formation of a precursor deposited on the support, the support is usually not pretreated with an alkyl-aluminum compound. Such treatment results in the formation of aluminum alkoxides that are chemically bonded to the carrier molecules. The present inventors have discovered that the use of such treated support in the catalyst system in the process of the present invention is not only unnecessary, but results in undesirable agglomeration when used in the production of high density polyethylene.

-3. , density (greater than 0.94 g.cm). This results in a lumpy product which is not free-flowing.

In addition, the present inventors have also discovered that the presence of a magnesium compound in a supported precursor does not significantly increase catalyst activity and therefore the magnesium compound is an unnecessary component.

Preferred cocatalysts of formula II include trialkyl aluminum compounds having 2 to 8 carbon atoms in each alkyl group. A particularly preferred cocatalyst is triisobutyl aluminum. The cocatalyst is used in an amount of between about 5 and about 500, preferably between about 10 and about 50 moles per 1 mol of vanadium.

Preferred promoters of formula III include fluoro, chloro or bromo substituted ethane or methane containing at least 2 halogen atoms attached to a carbon atom. Preferred promoters include CCl ^, CHCl ^, ^ CHjC, CBr ^, _g CFCl, CCl CH ^ CF ^ ^ and ClCClj. Particularly preferred promoters are methylene dichloride (CH ₂ C1 _2), 1,1,1-trichloroethane (CHjCClj) and chloroform (CHCip. For 1 mole of cocatalyst used is between about 0.1 and about 10, preferably between about 0.2 and about 2 parts by molar promoter.

The catalyst system of the present invention is produced by first preparing a supported precursor. In one embodiment, the vanadium compound is prepared by dissolving vanadium halide in an electrol donor at a temperature between about 20 ° C and the boiling point of the electron donor for several hours. The mixing is preferably carried out at about 65 ° C for about 3 hours or more. The vanadium compound thus produced can be carried out by adding the carrier in the form of a dry powder or suspension in an electron donor or other inert solvent. The liquid is removed by drying at a temperature of less than about 100 ° C for several hours, preferably at a temperature of about 45 to about 90 ° C for about 3 to 6 hours. The vanadium impregnated carrier is then mixed with a modifier dissolved in an inert solvent such as a hydrocarbon. The liquid is removed by drying at temperatures below about 70 ° C for several hours, preferably at a temperature between about 45 and about 65 ° C for 3 hours.

The cocatalyst and promoter are added to the supported precursor either before and / or during the polymerization reaction. The cocatalyst and the promoter are added either together or separately and either simultaneously or sequentially during the polymerization. The cocatalyst and the promoter are preferably added separately during the polymerization in the form of solutions in an inert solvent such as isopentane.

The ethylene polymerization is carried out in the gas phase using procedures well known in the art. Preferably, the polymerization is carried out in a continuous fluidized bed process. In this process, single portions of the catalyst system and monomers are fed into the reaction vessel and the polyethylene product is continuously removed from the reaction vessel. The density of the ethylene copolymer produced can vary over a wide range depending on the amount of alpha-olefin comonomer to be added and its type. The greater the molar proportion of alpha-olefin added, the lower the copolymer density is achieved.

The polymerization is carried out at a temperature below the sintering temperature of the polyethylene. The operating temperature is usually in the range of about 10 ° C to about 115 ° C. The preferred operating temperature varies depending on the desired density of the polyethylene. High density polyethylenes, i.e., densities greater than about 940 kg.m ^-3 , are produced at an operating temperature of between about 85 and about 115 ° C, preferably between about 90 and about 100 ° C. Low density polyethylenes, i.e. having a density in the range of about 910 to about 940 kg / m ³ , are preferably produced at an operating temperature of between about 75 and about 90 ° C. Very low density polyethylenes, i.e., less than about 910 kg / m 2, are preferably produced at an operating temperature of between about 10 and about 80 ° C. In the case of very low density polyethylenes, it is necessary to dilute the reaction mixture with a large amount of diluent gas to prevent the formation of polymer agglomerates and to maintain a continuous polymerization operation as described in related U.S. Pat. No. 250,660 to Union Carbide Corporation.

The fluidized bed reactor is operated at a pressure of up to 6,870 kPa and preferably between about 343 and about 2,340 kPa.

A transfer agent such as hydrogen may be used to terminate the polymer chains. A typical hydrogen to ethylene ratio will vary between about 0.001 and about 2.0 parts by molar hydrogen to 1 part by molar ethylene. The present inventors have found that the response to hydrogen is improved using the catalyst system of the invention, so that less hydrogen is required to produce polyethylene with an extremely low unsaturation content.

The following examples serve to illustrate the catalyst system and process of the invention. The examples are not intended to limit the scope of the invention.

The properties of py, unless the polymers produced in the examples are determined, are as follows.

test postProperties

Test procedure

Ash content The polyethylene is converted into ash which is weighed. The productivity defined as the number of parts by weight of polyethylene produced per 1 part by weight of the total catalyst can be calculated.

Bulk density (kg / m ³ )

Determined according to American Standard ASTM-D-1 895, Method B.

Density (kg.m ³ )

It is determined according to American Standard ASTM-1 605, based on plaques prepared according to American Standard ASTM-D-1 928, Procedure C. i

Fine (% by weight) Amount of polymer particles that pass through a sieve having a mesh size of 74.10 ^- ® m.

Melt Flow Index at Higher Load (g / 10 min) Determined according to ASTM-D-1 238, Condition F.

Melt Flow Index Diameter The ratio of the melt flow index at a higher load to the melt flow index at a lower load. The melt flow index at a lower load is measured according to American standard ASTM-D-1 238, condition E.

The Test Procedure property

Agglomeration of particles

The reactor is determined on a leaving basis by visual observation of the produced polyethylene.

Unsaturation (C = C / 1000 C) ^a Determined by infrared spectrophotometric measurement of absorbance (absorbance at 10.35 micrometres corresponding to trans-woollidene groups, 11.0 micrometres corresponding to terminal vinyl groups and 11.25 micrometres corresponding to hanging vinyl groups) 0.63 mm thick polymer molding. The unsaturation concentration is proportional to the absorbance relative to 0.025 mm divided by the absorbency (values used, the absorbptivity published by RJ deKock et al., In J. Polymer Science, Part B. 2, 339, (1964)).

Note:

³ Number of carbon-carbon double bonds per 1 000 carbon atoms.

Abbreviations used in the examples have the following meanings:

Designation Explanation of meaning DEAC Diethylaluminiumchlorid ED An electron donor compound TEAL Triethyl aluminum THF Tetrahydrofuran TIBA Triisobutylaluminium TnHAL Tri-n-hexyl aluminum EADC Ethylaluminium dichloride

The catalyst systems used in the examples are produced using these standard procedures. To a flask containing 4 L of anhydrous tetrahydrofuran was added 34 g (0.216 mol) of vanadium chloride. The mixture was stirred at 65 ° C for 5 hours under nitrogen until the vanadium chloride dissolved. To this solution was added 800 g of silica which was dehydrated by heating to 600 ° C and stirring was continued for 4 hours at 65 ° C. In Comparative Examples A through D, the silica was pretreated with 5.5% by weight triethyl aluminum. The flask was vented and the solution was dried to a sludge-like state at 70 ° C. The temperature was allowed to drop to 45 ° C and the solution was purged with nitrogen for 6 hours or until the tetrahydrofuran level in the resulting product reached 4-10% by weight. The impregnated silica produced by this process is a solid particulate material that contains 0.25 mmol vanadium per gram. Remove the solid from the flask and store under nitrogen.

Then, with the exception of Comparative Example C, a modifier is introduced using the following procedure. To a flask containing 4 liters of anhydrous isopentane is added 500 g of the impregnated silica described above. To this mixture was added a solution of diethyl aluminum chloride as a modifier in anhydrous hexane at a concentration of 25% by weight with stirring. The modifier was used in an amount such that the number of moles of modifier per mole of tetrahydrofuran in the vanadium compound shown in the examples . This mixture is heated to 45 ° C and purged with nitrogen for 3 hours or until the product is a free-flowing powder.

The vanadium precursor thus produced is then removed from the flask and stored under nitrogen.

Polyethylene is produced in a fluidized bed reactor using the following standard procedure and operating conditions summarized in Table I. Ethylene is copolymerized with the comonomer exemplified. The triisobutyl aluminum cocatalyst is added during the polymerization as a 5% by weight solution in Isopentane. Chloroform CHCl 3 is added, with the exception of Comparative Example D, as a 5% by weight solution in isopentane, unless otherwise stated, in proportion to the cocatalyst as exemplified.

Each polymerization is carried out continuously for more than one hour after reaching equilibrium at a pressure of about 2061 kPa and at the gas velocity, nitrogen gas concentration and temperature shown in Table I.

Examples 1 to 8 and Comparative Examples A to D

In these examples, high density ethylene copolymers are prepared using various catalyst systems. The above procedures are used and are operated on the basis of the parameters given in Table I. Examples 1 to 6 show an embodiment of the invention in which 1-butene is copolymerized. Examples 7 and 8 relate to another embodiment of the present invention wherein 1-hexene is copolymerized. In Comparative Examples A to D, an inert carrier was used which was chemically treated with an aluminum alkyl prior to impregnation. In Comparative Example C, a catalyst system without a modifier is used. In Comparative Example D, a catalyst system without a promoter is used.

The analysis of polyethylene using the test procedures described above is shown in Table I.

Tabulkal

Data relating to the use of the catalysts of the invention and comparative catalysts in the production of high density ethylene copolymers.

Example number 1 2 3 4 5 6 Catalyst: Prayer DEAC DEAC DEAC DEAC DEAC DEAC Promotor CHCl ₃ a CHCl ₃ a CHC1 ₃ I want ₃ I want ₃ I want ₃ Modifier / tetra- ratio hydrofuran 0.9 0.9 0.9 0.9 0.9 0.9 Pre-processing carriers nezpra- nezpra- nezpra- nezpra- nezpra- nezpra- cován cován cován cován cován cován Cocatalyst TIBA TIBA TIBA TIBA TIBA TIBA Promoter / coca- ratio analyzer 2,0-2,22 2,0-2,22 2 2 2 1.66 Aluminum / vanadium ratio 20-25 20-25 20-25 20-25 20-25 20-25 Polymerization: « Temperature (° C) 100 ° 100 ° 100 ° 100 ° 90 ° 100 ° Gas velocity (mS ¹ ) 0.61 0.61 0.61 0.61 0.61 0.61 Nitrogen pressure (% mole) 10 10 10 10 10 10 Komonomer 1-butene 1-butene 1-butene 1-butene 1-butene 1-butene Comonomer / ethylene ratio 0.006 0.006 0,002 0,002 0.006 0,002 Hydrogen / ethylene ratio 0,061 0.05 0.051 0,046 0,045 0,028 Yield per unit time and time (kg.h ^- .m ^-J ) ' 106 102 90 102 115 128

Table I continued

Example number 1 2 3 4 5 6 Polyethylene: Η · Density (kg.m) 957 958 958 958 956 954 Melt flow index at Higher load (g / 10 min) 33-38 23-27 34-38 23-27 35-38 23-25 melt index ratio 70-75 70-75 70-75 70-75 90-95 70-75 Bulk density (kg.m ³ ) 424 424 448 448 432 440 Fine particles (% by weight) 0.01 0.01 0.01 0.01 0.01 0.01 Ash (% by weight) 0.05 0.05 0.052 0.052 0.050 0,048 Agglomeration of particles small to small to small to small to small to small to none none none none none none Example number 7 8 AND (B) C D

Catalyst:

Modifier DEAC DEAC DEAC DEAC none DEAC Promotor CHCl3 I WANT ₃ I want ₃ I want ₃ I want ₃ none Modifier / tetra- ratio hydrofuran 0.9 0.9 0.25 0.95 - 0.95 Pre-processing carriers nezpra- nezpra- nezpra- nezpra- nezpra- nezpra- cován cován cován cován cován cován Cocatalyst TIBA TIBA TIBA TIBA TIBA TIBA Promoter / coca- ratio analyzer 1.33 1.33 1 2 2 - Aluminum / vanadium ratio 20-25 20-25 20 May 20 May 25 12 Polymerization: Temperature (° C) 100 ALIGN! 90 100 ALIGN! 100 ALIGN! 100 ALIGN! 100 ALIGN! Gas speed (ms ¹ ) 0.61 0.61 0.58 0.58 0.34 0.58 Nitrogen pressure (% molar) 16.5 20 May 15 Dec 15 Dec 15 Dec 15 Dec Komonomer 1-hexene 1-hexene 1-butene 1-butene 1-butene 1-butene Comonomer / ethylene ratio 0.010 0.011 0,002 0,002 0,002 0.009 Hydrogen / ethylene ratio 0,022 0,038 0,043 0.03 0,07 ^x 0,14 ^x: Yield per unit time and time (kg.h ^ .m ^) 59 61 88 64 64 64 Polyethylene: _3 Density (kg.m) 945 943 956-958 956-958 956-958 956 Flow index melted at higher load (g / 10 min) 5-6 5-6 20-22 20-22 20-22 20-22 Melt flow index ratio 70-75 90-95 70-75 70-75 70-75 75 -3 Bulk density (kg.m) 424 440 416-432 448-464 320-336 ^x 512 Fine particles (% by weight) 0.01 0.01 0.08 0.05 8 ^X _r xx 0 Ash (% by weight) 0,036 0,036 0,036 0,025-0,030 0,040-0,045 0,062 ^XX Agglomeration of particles small to small to strong strong none none none none

Comment:

In all Examples 1 to 8, polyethylene of high bulk density, low particulate content, low ash content (i.e. catalyst activity is high), good particle flow (no agglomeration problems) with good response to hydrogen (indicating a low hydrogen ratio) (monomer).

Examples A and B illustrate severe agglomeration problems.

(a) 1% by weight is used instead of 5% isopentane solution.

x_) Poor response to hydrogen, bulk density and higher content of fine particles.

xx) Poor hydrogen response, higher fine particle content and poorer activity.

The results shown in Table I show that the catalyst system of the present invention has a high activity as evidenced by a low ash content and provides products with the desired balance of properties, evidenced by a lower hydrogen to monomer ratio (improved hydrogen response), higher bulk density, improved particle flow and less fines. Conversely, the agglomeration in Comparative Examples A and B is very strong. In these examples, catalyst systems similar to the catalyst systems of the present invention were used, except that the supports were pretreated with alkyl-aluminum compounds. In addition, in the absence of a modifier, as in Comparative Example C, the hydrogen response decreases (as shown by the hydrogen to monomer ratio increase), the bulk density decreases and the proportion of fine particles is greater, all of which cause less desirable values. Similarly, in the absence of a promoter, as in Comparative Example D, the response to hydrogen is less, the fine particle content increases and the activity of the catalyst decreases, all resulting in less desirable values.

Example 9 and Comparative Examples E and F

These examples demonstrate better saturation of the polyethylene produced using the catalyst system and method of the invention compared to the results of the comparative experiments. The results are summarized in Table II. Example 9 was carried out using the procedures described above to give the product an ethylene-butene copolymer having a tabulated level of unsaturation. In Comparative Example E, similar conditions were employed using triethyl aluminum as the cocatalyst but without diethylaluminum chloride as the modifier. The polyethylene produced according to the present invention preferably has reduced unsaturation compared to the product obtained using a very similar catalyst system as in Example E.

Comparative Example F shows the unsaturation of polyethylene produced by an alternative process previously known and demonstrates that this polyethylene has a significantly higher level of unsaturation, which leads to instability of the polymer, which degrades over time. Polyethylene produced using the catalyst system and process of the present invention, on the other hand, exhibits excellent stability due to very low polymer unsaturation.

Table II

Comparison of polyethylene unsaturation.

Example 9 Comparative Example Comparative example Catalyst Modified ^a Unmodified * ³ Silylchromate ^c vanadium vanadium Unsaturation (C = C / 1000 C): Trans-vinyl 0,010 8 0,019 7 0,038 Terminal vinyl 0,010 4 0.050 8 1,148 Hanging vinylidene 0,061 9 0,081 2 0.106 Total 0,083 1 0,151 7 1,292

Comment:

a) the catalyst VCl ₃ / THF / SiO ₂ / DAEC / TIBA / CHCl ₃ according to the invention was used

b) a catalyst VCl ₃ / THF / SiO ₂ / TEAL / CHCl _{3 is} used at a polymerization temperature of 90 ° C,

c) the polymerization method of U.S. Patent No. 3,324,095 to Carrick et al.

Examples 10 to 13

In these examples, low density ethylene copolymers are prepared using the procedures and sieves listed in Table III above. Examples 10 to 12 illustrate the copolymerization of ethylene with 1-butene. Example 13 serves to illustrate the copolymerization of ethylene with propylene. In all these examples, triethyl aluminum is used as the cocatalyst. The results shown in Table III show that the catalyst system of the present invention has a high activity and, as well as the preparation of high density ethylene copolymers, provides products with the desired property profile in the preparation of low density ethylene copolymers.

Table III

Production of low density ethylene copolymers.

Example number 10 11 12 13 Catalyst: Modifier DEAC DEAC DEAC DEAC Promotor CHC1 ₃ CHC1 ₃ I want ₃ I want ₃ Modifier / tetra- ratio hydrofuran 1.0 1.0 1.0 1.0 Carrier pretreatment not processed not processed not processed not processed Cocatalyst TEAL TEAL TEAL TEAL The promoter / cocatalyst ratio 1.54 1.31 1,22 1.0 Aluminum / vanadium ratio 40 40 40 35 Polymerization: Temperature (° C) 85 85 85 90 Komonomer 1-butene 1-butene 1-butene propylene Comonomer / ethylene ratio 0.139 0,086 0,054 0.13 Hydrogen / ethylene ratio 0,026 0.016 0.014 0.02 Yield per unit of space and time (kg.h ^ .m ^) 83 82 82 67 Polyethylene: Density (kg.m ^) 915 922 927 922 Melt flow index at higher load (g / 10 min) 459 9.5 3.4 19 Dec Melt flow index ratio 49 - - - Bulk density (kg.m) 378 374 378 448 Fine particles (% by weight) 0 0 0 0 Ash (% by weight) 0,039 0.071 0,082 0.10 Agglomeration of particles small to small to small to small to none none none none

Examples 14 to 19

In these examples, very low density ethylene-propylene copolymers are prepared using the procedures and conditions outlined in Table IV above. In Example 14, triethyl aluminum was used as the cocatalyst in place of triisobutyl aluminum. The results shown in Table IV show that the catalyst system of the present invention can also be used to produce very low density ethylene copolymers having a desired property profile, wherein the activity of the catalyst system is high.

Production of very low density ethylene copolymers.

Example number 14 15 Dec 16 17 18 19 Dec Catalyst: Modifier DEAC DEAC DEAC DEAC DEAC DEAC Promotor Modifier / tetra- ratio CHCl3 CHC1 ₃ CHC1 ₃ CHC1 ₃ CHCl3 I want ₃ hydrofuran 1.7 1.7 1.7 1.7 1.7 1.7 Pre-processing nezpra- nezpra- nezpra- nezpra- nezpra- nezpra- carriers cován cován cován cován cován cován Cocatalyst Promoter / coca- ratio TEAL TIBA TIBA TIBA TIBA TIBA analyzer 1.0. 1.0 1.0 1.0 1.0 1.0 Aluminum / vanadium ratio 40 40 40 40 43 45 Polymerization: Temperature (° C) 75 70 65 50 40 36 Gas speed (ms ^-1 ) 0.46 0.46 0.46 0.46 0.46 0.46 Nitrogen pressure (* molar) 45 50 59 57 60 60 Komonomer propyle: n propylene propylene propylene propylene propylene Comonomer / ethylene ratio 0.22 0.24 0.26 0.35 0.31 0.34 Hydrogen / ethylene ratio 0.01 0.007 0.006 0.006 0,002 tracks

Yield per unit

time and time (kg.h ³ .m ³ ) 66 75 61 43 69 67 Polyethylene: Density (kg.m ^-3 ) 906 895 894 882 871 865 Melt flow index at higher load (g / 10 min) 27 9 6 20 May 3 1 The melt index ratio 41 53 64 51 - - Bulk density (kg.m ³ ) 432 384 368 320 368 368 Fine particles (% by weight) - - 0.05 0 0 0 Ash (% by weight) 0.10 0,082 0.11 - 0.14 0.07

Examples 20 to 22

In these examples, ethylene is copolymerized with 1-hexene using catalyst systems containing tri-n-hexyl aluminum, ethylaluminum dichloride or triethyl aluminum as a modifier. The above procedures were carried out under the conditions set forth in Table V. The modifier was treated with vanadium chloride impregnated silica containing 0.2 mmol of vanadium per 1 gram of vanadium chloride impregnated silica. In each of the examples, triethyl aluminum is used as the cocatalyst. The results summarized in Table V show that various modifiers can be used in the catalyst systems of the invention.

Table V

Use of catalysts with various modifiers.

Example number 20 21 22

Catalyst: Modifier TnHAL EADC TEAL Promotor I want ₃ CHC1 ₃ I WANT.

Table V continued

Example number 20 May 21 22nd Modifier / tetrahydrofuran ratio 0.84 0.84 0.84 Carrier pretreatment not processed not processed not processed Cocatalyst TEAL TEAL TEAL The promoter / cocatalyst ratio 1.1 1.1 1.0 Aluminum / vanadium ratio 102 37 38 Polymerization: Temperature (° C) 90 90 90 Gas speed (ms ^-2 ) 0.55 0.55 0.55 Nitrogen pressure (% mole) 4 10 11.3 Komonoraer 1-hexene 1-hexene 1-hexene Comonomer / ethylene ratio 0,001 8 0,001 8 0.003 Hydrogen / ethylene ratio 0,068 0,067 0,076 ' Yield per space and time (kg.h ^ .m ² ) 69 128 102 Polyethylene: Density (kg.ra ² ) 0,957 0,955 0,957 Melt flow index at higher load (g / 10 min) 28-30 27-29 23-24 Melt flow index ratio 90-95 95-100 90-100 Bulk density (kg.m ^-2 ) 464 451 467 Fine particles (% by weight) 3,4 ^a 3,3 ^a 1, 6 ^and Ash (% by weight) 0,041 0,056 0,054 Agglomeration of particles little to no little to no little to no Note: (a) passes a sieve with a mesh size of 130 .10 $ instead of 74 .10 ~ ⁶ ) m.

SUBJECT OF THE INVENTION

Claims (9)

SUBJECT OF THE INVENTION (1) the vanadium compound which is the reaction product; (a) vanadium halide, wherein the halogen is chlorine, bromine or iodine; and (b) an electron donor, which is a liquid organic Lewis base in which vanadium halide is soluble; A process for the production of an ethylene homopolymer or a copolymer of ethylene with at least one C 3 -C 10 alpha-olefin by gas-phase polymerization using a modified vanadium catalyst, characterized in that the monomer or a mixture thereof is introduced at a temperature of 10 to 115 ° C contact with a catalytic system comprising (A) a precursor deposited on a carrier consisting of: 2. The method of claim 1 wherein the electron donor is selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic esters, aliphatic ketones, aliphatic amines, aliphatic alcohols, alkyl and cycloalkyl ethers, and mixtures thereof. 2) a modifier of formula I MX _and (I) where 257260, is boron or a radical All ^ _ _a) in which R are each independently alkyl with the proviso that the total number of aliphatic carbon atoms in any group R is not greater than 14 means a chlorine, bromine or iodine, a is 0, 1, or With the proviso that when M is boron, a is 3 and 3. A process according to claim 1, wherein the vanadium halide comprises chlorine, the electron donor is an alkyl or cycloalkyl ether, the modifier is an alkyl aluminum or mono (C1 -C6) alkyl or boron trichloride, the carrier is silica, the cocatalyst is trialkyl aluminum having 2 to 8 carbon atoms in each alkyl radical and promoter is ethane or methane substituted with fluorine, chlorine or bromine. 3) a solid inert carrier, consisting of silica or alumina, on which the vanadium compound and modifier are deposited. B) a cocatalyst of formula II air ₃ wherein R is as defined above C) a promoter of formula III ^R b ^CX (4-b) wherein (II) (III) R 'is hydrogen or unsubstituted or halogenated alkyl having up to 6 carbon atoms X 'is halogen and b is 0, 1 or 2. 4. The method of claim 1 wherein the vanadium halide is vanadium chloride, the electron donor is tetrahydrofuran, the modifier is diethylaluminum chloride, the carrier is silica, the cocatalyst is triisobutyl aluminum or triethyl aluminum, and the promoter is chloroform. 5. The process according to any one of items 1 to 4 for producing polyethylene having a density greater than or equal to about 5% 940 kg / m ³ , characterized in that the polymerization is carried out at a temperature in the range from 85 to 115 ° C. 6. Process according to claim 5, characterized in that a monomer feedstock comprising ethylene or a mixture of ethylene with propylene, 1-butene or 1-hexene is used. 7. A process according to any one of items 1 to 4 for the production of polyethylene having a density in the range from 910 to 940 kg.m ^-3 , characterized in that the polymerization is carried out at a temperature in the range from 75 to 90 ° C. 8. A process according to any one of items 1 to 4 for the production of polyethylene having a density of less than 910 kg.m wherein the polymerization is carried out at a temperature in the range of from 10 to 80 ° C. 9. A process according to claim 7 or 8, wherein a monomer feedstock comprising a mixture of ethylene with propylene, 1-butene or 1-hexene is used.