Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/04—Polymerisation in solution
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/12—Polymerisation in non-solvents
  • C08F2/16—Aqueous medium
  • C08F2/18—Suspension polymerisation
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/34—Polymerisation in gaseous state
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/602—Component covered by group C08F4/60 with an organo-aluminium compound
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/607—Catalysts containing a specific non-metal or metal-free compound
  • C08F4/609—Catalysts containing a specific non-metal or metal-free compound organic
  • C08F4/6093—Catalysts containing a specific non-metal or metal-free compound organic containing halogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F4/00—Polymerisation catalysts
  • C08F4/42—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors
  • C08F4/44—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides
  • C08F4/60—Metals; Metal hydrides; Metallo-organic compounds; Use thereof as catalyst precursors selected from light metals, zinc, cadmium, mercury, copper, silver, gold, boron, gallium, indium, thallium, rare earths or actinides together with refractory metals, iron group metals, platinum group metals, manganese, rhenium technetium or compounds thereof
  • C08F4/607—Catalysts containing a specific non-metal or metal-free compound
  • C08F4/609—Catalysts containing a specific non-metal or metal-free compound organic
  • C08F4/6094—Catalysts containing a specific non-metal or metal-free compound organic containing oxygen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers

Definitions

• the present invention relates to a polymerization process for the production of a polyethylene.
• the polyethylene has a low level of extractables.
• Films produced from the polyethylene are characterized by having high strength properties.
• halogenated hydrocarbons are monohalogen and polyhalogen substituted saturated or unsaturated aliphatic, alicyclic, or aromatic hydrocarbons having 1 to 12 carbon atoms.
• exemplary aliphatic compounds include methyl chloride, methyl bromide, methyl iodide, methylene chloride, methylene bromide, methylene iodide, chloroform, bromoform, iodoform, carbon tetrachloride, carbon tetrabromide, carbon tetraiodide, ethyl chloride, ethyl bromide, 1,2-dichloroethane, 1,2-dibromoethane, methylchloroform, perchloroethylene and the like.
• Electron donors typically known as Lewis Bases, when employed during the catalyst preparation step are referred to as internal electron donors.
• Electron donors when utilized other than during the catalyst preparation step are referred to as external electron donors.
• the external electron donor may be added to the preformed catalyst, to the prepolymer, and/or to the polymerization medium.
• electron donors include carboxylic acids, carboxylic acid esters, alcohols, ethers, ketones, amines, amides, nitriles, aldehydes, thioethers, thioesters, carbonic esters, organosilicon compounds containing oxygen atoms, and phosphorus, arsenic or antimony compounds connected to an organic group through a carbon or oxygen atom.
• R is a hydrocarbon group, containing from 1 to 100 carbon atoms and from 0 to 10 oxygen atoms, connected to the Group 13 element by a carbon or oxygen bond.
• the present inventors have unexpectedly discovered that a particular combination of a Ziegler-Natta catalyst, at least one halogenated hydrocarbon, as a co-catalyst at least one compound of the formula, X n ER 3-n , wherein,
• the compound used herein as an external electron donor is any compound containing at least one carbon-oxygen-carbon linkage (C-O-C) of the formula R 1 -O(- R -O) n -R 3 where n ranges from 0 to 30, and R 1 , R 2 and R 3 independently contain from 1 to 30 carbon atoms and from 0 to 30 heteroatoms of an element, or mixtures thereof, selected from Groups 13, 14, 15, 16 and 17 of the Periodic Table of Elements, and further wherein R 1 , R 2 and/or R 3 can be linked and form part of a cyclic or polycyclic structure.
• C-O-C carbon-oxygen-carbon linkage
• hydrocarbons containing from 1 to 30 carbon atoms and from 1 to 30 heteroatoms of an element, or mixtures thereof from Groups 13, 14, 15, 16 and 17 of the Periodic Table of Elements such as, for example, B 1-30 borohydrocarbons, Sij .30 silahydrocarbons, P 1-30 phosphahydrocarbons, S ⁇ -30 thiahydrocarbons, Cl 1-30 chlorohydrocarbons and halogenated hydrocarbons containing mixtures of halogens.
• dimethyl ether dimethyl ether; diethyl ether; dipropyl ether; d ⁇ sopropyl ether; dibutyl ether; dipentyl ether; dihexyl ether; dioctyl ether; diisoamyl ether; di-tert-butyl ether; diphenyl ether; dibenzyl ether; divinyl ether; diallyl ether; dicyclopropyl ether; dicyclopentyl ether; dicyclohexyl ether; allyl methyl ether; allyl ethyl ether; allyl cyclohexyl ether; allyl phenyl ether; allyl benzyl ether; allyl 2-tolyl ether; allyl 3-tolyl ether; benzyl methyl ether; benzyl ethyl ether; benzyl isoamyl ether; benzyl chloromethyl ether;
• C 2-2 o cyclic compounds where R 1 and R 3 are linked and form part of a cyclic or polycyclic structure such as, for example, ethylene oxide; propylene oxide; 1,2-epoxybutane; cyclopentene oxide; epichlorohydrin; trimethylene oxide; 3,3-dimethyloxetane; furan; 2,3-dihydrofuran; 2,5-dihydrofuran; tetrahydrofuran; 2-methyltetrahydrofuran; 2,5-dimethyltetrahydrofuran; 4,5-dihydro- 2-methylfuran; 2-methylfuran; 2,5-dimethylfuran; 3-bromofuran; 2,3-benzofi ⁇ ran; 2- methylbenzofuran; dibenzofuran; phthalan; xanthene; 1,2-pyran; 1,4-pyran; tetrahydropyran; 3-methyltetrahydropyran; 4-chlorotetrahydropyran;
• Exemplary compounds containing more than one C-O-C linkage include alkyl, alkenyl, dienyl and aryl substituted compounds of the formula R 1 -O(-R 2 -O) n -R 3 where n ranges from 1 to 30.
• dimethoxymethane 1,1- dimethoxy ethane; lJJ-trimethoxyethane; lJ,2-trimethoxyethane; 1J- dimethoxypropane; 1,2-dimethoxypropane; 2,2-dimethoxypropane; 1,3- dimethoxypropane; lJ,3-trimethoxypropane; 1,4-dimethoxybutane; 1,2- dimethoxybenzene; 1,3-dimethoxybenzene; 1,4-dimethoxybenzene; ethylene glycol dimethyl ether; ethylene glycol diethyl ether; ethylene glycol divinyl ether; ethylene glycol diphenyl ether; ethylene glycol tert-butyl methyl ether; ethylene glycol tert- butyl ethyl ether; di( ethylene glycol) dimethyl ether; di( ethylene glycol) diethyl ether; di( ethylene glycol) di
• C 3-2 o cyclic compounds where R 1 , R 2 and/or R 3 are linked and form part of a cyclic or polycyclic structure.
• Specific examples are 2,5-dimethoxyfuran; 2-methoxyfuran; 3- methoxyfuran; 2-methoxytetrahydropyran; 3-methoxytetrahydropyran; 1,3-dioxolane; 2-methyl- 1,3-dioxolane; 2,2-dimethyl- 1,3-dioxolane; 2-ethyl-2-methyl- 1,3-dioxolane; 2, 2-tetramethylene- 1,3-dioxolane; 2, 2-pentamethylene- 1,3-dioxolane; 2-vinyl- 1,3- dioxolane; 2-chloromethyl- 1,3-dioxolane; 2-methoxy- 1,3-dioxolane; 1,4- dioxaspiro[4J]non-6-ene; 1,4,9
• the co-catalyst used in the process of the present invention is at least one compound of the formula
• E is an element from Group 13 of the Periodic Table of Elements such as boron, aluminum and gallium; and R is a hydrocarbon group, containing from 1 to 100 carbon atoms and from 0 to 10 oxygen atoms, connected to the Group 13 element by a carbon or oxygen bond.
• alkylaluminum sesquialkoxides such as methylaluminum sesquimethoxide, ethylaluminum sesquiethoxide; «-butylaluminum sesqui- «-butoxide and the like.
• alkylaluminum sesquihalides such as methylaluminum sesquichloride; ethylaluminum sesquichloride; isobutylaluminum sesquichloride; ethylaluminum sesquifluoride; ethylaluminum sesquibromide; ethylaluminum sesquiiodide and the like.
• trialkylaluminums such as trimethylaluminum, triethylaluminum, tri- «-propylaluminum, tri-n-butylaluminum, triisobutylaluminum, tri-rc-hexylaluminum, trusohexylaluminum, tri-2- methylpentylaluminum, tri-n-octylaluminum, tri- «-decylaluminum; and dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride, diethylaluminum bromide and diethylaluminum iodide; and alkylaluminum sesquihalides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, n-
• trialkylaluminums such as trimethylaluminum, triethylaluminum, tri-n-propylaluminum, tri-M-butylaluminum, triisobutylaluminum, tri-tt-hexylaluminum, triisohexylaluminum, tri-2- methylpentylaluminum, tri- «-octylaluminum and dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride and alkylaluminum sesquihalides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, rc-butylaluminum sesquichloride and isobutylaluminum sesquichloride.
• trialkylaluminums such as trimethylaluminum, triethylaluminum,
• Any halogenated hydrocarbon may be used in the process of the present invention. If desired more than one halogenated hydrocarbon can be used. Typical of such halogenated hydrocarbons are monohalogen and polyhalogen substituted saturated or unsaturated aliphatic, alicyclic, or aromatic hydrocarbons having 1 to 12 carbon atoms.
• aromatic compounds are fluorobenzene; chlorobenzene; bromobenzene; iodobenzene; 1,2-difluorobenzene; 1,2-dichlorobenzene; 1,2- dibromobenzene; 1,2-d ⁇ odobenzene; 1,3-difluorobenzene; 1,3-dichlorobenzene; 1,3- dibromobenzene; 1,3-diiodobenzene; 1,4-difluorobenzene; 1,4-dichlorobenzene; 1,4- dibromobenzene; 1,4-diiodobenzene; l-bromo-2-fluorobenzene; l-bromo-2- chlorobenzene; l-bromo-2-iodobenzene; l-chloro-2-fluorobenzene; l-chloro-2- iodobenzene; l-fluoro-2-
• Preferred for use in the process of the present invention are dichloromethane; dibromomethane; chloroform; carbon tetrachloride; bromo chloromethane; chlorofluoromethane; bromodichloromethane; chlorodifluromethane; fluorodichloromethane; chlorotrifluoromethane; fluorotrichloromethane; 1,2- dichloroethane; 1,2-dibromoethane; 1-chloro- 1-fluoroethane; 1-chloro- 1,1- difluoroethane; 1-chloro- 1,2-difluoroethane; 2-chloro- lJ-difluoroethane; 1,1,1,2- tetrafluoroethane; lJJ,2-tetrachloroethane; 2-chloro- lJJ-trifluoroethane; 1,1- dichloro-2,2-difluoroethane; 1,2-dichloro
• the polymerization process of the present invention may be carried out using any suitable process.
• a particularly desirable method for producing polyethylene polymers according to the present invention is a gas phase polymerization process preferably utilizing a fluidized bed reactor.
• This type reactor and means for operating the reactor are well known and completely described in U.S Patents Nos. 3,709,853; 4,003,712; 4,011,382; 4,012,573; 4,302,566; 4,543,399; 4,882,400; 5,352,749; 5,541,270; Canadian Patent No. 991,798 and Belgian Patent No. 839,380.
• These patents disclose gas phase polymerization processes wherein the polymerization medium is either mechanically agitated or fluidized by the continuous flow of the gaseous monomer and diluent. The entire contents of these patents are incorporated herein by reference.
• polyenes such as 1,3-hexadiene, 1,4-hexadiene, cyclopentadiene, dicyclopentadiene, 4-vinylcyclohex-l-ene, 1,5-cyclooctadiene, 5- vinylidene-2-norbornene and 5-vinyl-2-norbornene, and olefins formed in situ in the polymerization maxim
• olefins are formed in situ in the polymerization medium, the formation of linear polyethylenes containing long chain branching may occur.
• the polymerization reaction of the present invention is carried out in the presence of a Ziegler-Natta type catalyst.
• the catalyst can be introduced in any manner known in the art.
• the catalyst can be introduced directly into the polymerization medium in the form of a solution, a slurry or a dry free flowing powder.
• the catalyst can also be used in the form of a deactivated catalyst, or in the form of a prepolymer obtained by contacting the catalyst with one or more olefins in the presence of a co-catalyst.
• the transition metal is selected from the group consisting of titanium, zirconium, vanadium and chromium, and in a still further preferred embodiment, the transition metal is titanium.
• the Ziegler-Natta catalyst can optionally contain magnesium and chlorine. Such magnesium and chlorine containing catalysts may be prepared by any manner known in the art.
• the organometaUic co-catalyst compound used to form the prepolymer can be any organometaUic compound containing a metal of Groups 1, 2, 11, 12, 13 and 14 of the above described Periodic Table of the Elements. Exemplary of such metals are Uthiu , magnesium, copper, zinc, boron, silicon and the like. However, when a prepolymer is employed, a co-catalyst of the above formula X n ER 3 ⁇ is sti utilized as the co-catalyst in the polymerization medium.
• the external electron donor and/or the halogenated hydrocarbon can, if desired, be added to the prepolymer.
• the catalyst system may contain conventional components in addition to the transition metal component, the external electron donor defined herein, the halogenated hydrocarbon and the co-catalyst component. For example, there may be added any magnesium compound known in the art.
• the co- catalyst is added to the polymerization medium in any amount sufficient to effect production of the desired polyethylene. It is preferred to utilized the co-catalyst in a molar ratio of co-catalyst to transition metal component of the Ziegler-Natta catalyst ranging from about 1: 1 to about 100: 1. In a more preferred embodiment, the molar ratio of co-catalyst to transition metal component ranges from about 1 : 1 to about 50: 1. In carrying out the polymerization process of the present invention the external electron donor is added in any manner.
• the external electron donor may be added to the preformed catalyst, to the prepolymer during the prepolymerization step, to the preformed prepolymer and/or to the polymerization medium.
• the external electron donor may optionaUy be premixed with the co- catalyst.
• the external electron donor is added in any amount sufficient to effect production of the desired polyethylene. It is preferred to incorporate the external electron donor in a molar ratio of external electron donor to transition metal component of the Ziegler-Natta catalyst ranging from about 0.01: 1 to about 100: 1. In a more preferred embodiment, the molar ratio of external electron donor to transition metal component ranges from about 0J J to about 50: 1.
• the halogenated hydrocarbon is added to the polymerization medium in any amount sufficient to effect production of the desired polyethylene. It is preferred to incorporate the halogenated hydrocarbon in a molar ratio of halogenated hydrocarbon to transition metal component of the Ziegler-Natta catalyst ranging from about 0.01 : 1 to about 100: 1. In a more preferred embodiment, the molar ratio of halogenated hydrocarbon to transition metal component ranges from about 0.001: 1 to about 1:1.
• the molecular weight of the polyethylene produced by the present invention can be controUed in any known manner, for example, by using hydrogen. The molecular weight control may be evidenced by an increase in the melt index (I 2 ) of the polymer when the molar ratio of hydrogen to ethylene in the polymerization medium is increased.
• the molecular weight distribution of the polyethylene produced by the present invention is expressed by the melt flow ratio (MFR).
• MFR melt flow ratio
• the polyethylenes have MFR values varying from about 24 to about 34, and densities ranging from about 0.880gm/cc to about 0.964gm/cc.
• the polyethylenes of the present invention may be fabricated into films by any technique known in the art.
• films may be produced by the weU known cast film, blown film and extrusion coating techniques.
• the polyethylenes may be fabricated into other articles of manufacture, such as molded articles, by any of the weU known techniques.
• an approximately 1 square inch film test specimen having a thickness ⁇ 4 mils weighing 2.5 ⁇ 0.05 grams is placed into a tared sample basket and accurately weighed to the nearest 0.1 milligram.
• the sample basket containing the test specimen is then placed in a 2-Uter extraction vessel containing approximately 1 liter of n- hexane.
• the basket is placed such that it is totaUy below the level of n- hexane solvent.
• the sample resin film is extracted for 2 hours at 49.5 ⁇
• the basket is raised above the solvent level to drain momentarily.
• the basket is removed and the contents are rinsed by immersing several times in fresh n-hexane.
• the basket is aUowed to dry between rinsing.
• the excess solvent is removed by briefly blowing the basket with a stream of nitrogen or dry air.
• the basket is placed in the vacuum oven for 2 hours at 80 ⁇ 5°C. After 2 hours, it is removed and placed in a desiccator to cool to room temperature (about 1 hour). After cooling, the basket is reweighed to the nearest 0.1 milligram. The percent n-hexane extractable content is then calculated from the weight loss of the original sample.
• the Ziegler-Natta catalyst was used in prepolymer form, in Examples 1-7 herein, and was prepared in accordance with Example 1-b of European Patent Application EP 0 703 246 Al. A prepolymer containing about 34 grams of polyethylene per miUimole of titanium was thus obtained.
• the reactor contains a fluidized bed consisting of a polyethylene powder made up of particles with a weight-average diameter of about 0.5 mm to about 1.4 mm.
• the gaseous reaction mixture which contains ethylene, olefin comonomer, hydrogen, nitrogen and minor amounts of other components, passes through the fluidized bed under a pressure ranging from about 290 psig to about 300 psig with an ascending fluidization speed, referred to herein as fluidization velocity, ranging from about 1.8 feet per second to about 2.0 feet per second.
• a Ziegler-Natta catalyst as described above, in prepolymer form, is introduced intermittently into the reactor.
• the said catalyst contains magnesium, chlorine and titanium.
• the prepolymer form contains about 34 grams of polyethylene per millimole of titanium and an amount of tri-n- octylaluminum (TnOA) such that the molar ratio, Al/Ti, is equal to about 1.1:1.
• TnOA tri-n- octylaluminum
• the Ziegler-Natta catalyst is introduced directly into the reactor without having been formed into a prepolymer. The rate of introduction of the prepolymer or catalyst into the reactor is adjusted for each given set of conditions in achieving the desired production rate.
• a solution of trimethylaluminum (TMA) in n-hexane at a concentration of about 2 weight percent is introduced continuously into the line for recycling the gaseous reaction mixture, at a point situated downstream of the heat transfer means.
• the feed rate of co-catalyst is expressed as a molar ratio of TMA to titanium (TMA/Ti), and is defined as the ratio of the co-catalyst feed rate (in moles of TMA per hour) to the catalyst or prepolymer feed rate (in moles of titanium per hour).
• a solution of chloroform (CHC1 3 ) in n-hexane, at a concentration of about 0.5 weight percent, is introduced continuously into the line for recycling the gaseous reaction mixture.
• the feed rate of the halogenated hydrocarbon is expressed as a molar ratio of CHC1 3 to titanium (CHC1 3 /Ti), and is defined as the ratio of the CHC1 3 feed rate (in moles of CHC1 3 per hour) to the catalyst or prepolymer feed rate (in moles of titanium per hour).
• Tetrahydrofuran (THF) when utilized in the foUowing examples, was the external electron donor.
• a solution of THF in n-hexane, at a concentration of about 1 weight percent, can be introduced continuously into the line for recycling the gaseous reaction mixture.
• the feed rate of THF is expressed as a molar ratio of THF to titanium (THF/Ti), and is defined as the ratio of the THF feed rate (in moles of THF per hour) to the catalyst or prepolymer feed rate (in moles of titanium per hour).
• the productivity of the catalyst or prepolymer is the ratio of pounds of polyethylene produced per pound of catalyst or prepolymer added to the reactor.
• the activity of the catalyst or prepolymer is expressed as grams of polyethylene per millimole titanium per hour per bar of ethylene pressure.
• the process conditions are given in Table 1 and the resin properties are given in Table 2.
• the molar ratio of TMA to titanium was 7.
• the molar ratio of CHC1 3 to titanium was 0.06.
• the process was conducted with the addition of tetrahydrofuran (THF) as an external electron donor at a molar ratio of THF to titanium of 3.
• 1- Hexene was used as comonomer.
• THF tetrahydrofuran
• a linear polyethylene free from agglomerate was withdrawn from the reactor at a rate of 206 lb/h (pounds per hour).
• the productivity of the catalyst was 179 pounds of polyethylene per pound of prepolymer which corresponds to an activity of 261 grams polyethylene per millimole titanium per hour per bar of ethylene partial pressure.
• the linear polyethylene had a density of 0.918 g/cc and a melt index MI 2.16 , 1 2 , of 0.9 dg/min.
• the Melt Flow Ratio, I21/I2 was 33 and the ether extractables were 4.8 % by weight.
• the dart impact was 200 grams and the MD ⁇ EAR and TD ⁇ EAR were 450 and 500, respectively.
• the process conditions are given in Table 1 and the resin properties are given in Table 2.
• the molar ratio of triethylaluminum (TEAL) to titanium was 7.
• the molar ratio of CHCI 3 to titanium was 0.06.
• the molar ratio of THF to titanium was 3.
• 1-Hexene was used as comonomer. Under these conditions a linear polyethylene free from agglomerate was withdrawn from the reactor at a rate of 197 lb/h.
• the productivity of the catalyst was 122 pounds of polyethylene per pound of prepolymer which corresponds to an activity of 168 grams polyethylene per millimole titanium per hour per bar of ethylene partial pressure.
• the linear polyethylene had a density of 0.918 g/cc and a melt index MI2.16, 12, of 0.9 dg/min.
• the Melt Flow Ratio, I21/I2 was 31 and the ether extractables were 3.6
• the process conditions are given in Table 1 and the resin properties are given in Table 2.
• the molar ratio of TEAL to titanium was 13.
• the molar ratio of CHC1 3 to titanium was 0.06.
• the molar ratio of THF to titanium was 3.
• 1-Hexene was used as comonomer.
• a linear polyethylene free from agglomerate was withdrawn from the reactor at a rate of 207 lb/h.
• the productivity of the catalyst was 150 pounds of polyethylene per pound of prepolymer which corresponds to an activity of 216 grams polyethylene per millimole titanium per hour per bar of ethylene partial pressure.
• Example 1 A review of the data shown in Tables 1 and 2 reveal the unexpectedly superior results obtained for the polyethylene produced utilizing the process of the present invention, as shown in Examples 1, 3 and 4. More particularly, as shown in Example 1, wherein TMA as co-catalyst, and an external electron donor such as THF, and CHC1 3 are utilized in the polymerization process, a polyethylene is produced having a level of Dart Impact Strength more than twice as great as the polyethylene produced in Example 2 wherein TMA and CHC1 3 are utilized but in the absence of an external electron donor.
• the resultant polyethylene has a reduced level of extractables as compared with the polyethylene of Example 2 prepared utilizing TMA and CHC1 3 without an external electron donor.
• the dart impact values of the polyethylenes of Examples 3 and 4 are substantially similar to the dart impact value of the polyethylene of Example 2.
• the polyethylene produced in accordance with the present invention utilizing the combination of an organoaluminum as co-catalyst, CHCI 3 and an external electron donor is characterized by having a narrower molecular weight distribution, as evidenced by Melt Flow Ratio values, as compared with the polyethylene of Example 2. It is further to be noted that other physical properties of the polyethylenes of Examples 1, 2, 3 and 4 are substantially similar.
• Examples 5, 6 and 7 are intended to demonstrate that similar results are obtainable when using olefins such as 1-butene, 1-pentene and 1-hexene as the comonomer with ethylene.
• the process conditions are given in Table 3 and the resin properties are given in Table 4.
• the molar ratio of TMA to titanium was 6.
• the molar ratio of CHC1 3 to titanium was 0.06.
• the molar ratio of THF to titanium was 3.
• 1-Hexene was used as comonomer.
• a linear polyethylene free from agglomerate was withdrawn from the reactor at a rate of 196 lb/h.
• the productivity of the catalyst was 168 pounds of polyethylene per pound of prepolymer which corresponds to an activity of 259 grams polyethylene per millimole titanium per hour per bar of ethylene partial pressure.
• the linear polyethylene had a density of 0.908 and a melt index MI 2.16 - I 2 , of 0.6 dg/min.
• the Melt Flow Ratio, I21/I2 was 34 and the ether extractables were 5.2 % by weight.
• the dart impact was greater than 1500 grams and the MD ⁇ EAR and TD TEAR were 700 and 750, respectively.
• the process conditions are given in Table 3 and the resin properties are given in Table 4.
• the molar ratio of TMA to titanium was 7.
• the molar ratio of CHCI 3 to titanium was 0.06.
• the molar ratio of THF to titanium was 3. Under these conditions a linear polyethylene free from agglomerate was withdrawn from the reactor at a rate of 200 lb/h.
• the productivity of the catalyst was 129 pounds of polyethylene per pound of prepolymer which corresponds to an activity of 239 grams polyethylene per millimole titanium per hour per bar of ethylene partial pressure.
• the linear polyethylene had a density of 0.908 and a melt index MI2.16, 12, of 0.5 dg/min.
• the Melt Flow Ratio, I 2 1/I2 was 31 and the ether extractables were 3.1 % by weight.
• the process conditions are given in Table 3 and the resin properties are given in Table 4.
• the molar ratio of TMA to titanium was 7.5.
• the molar ratio of CHC1 3 to titanium was 0.06.
• the molar ratio of THF to titanium was 3. Under these conditions a linear polyethylene free from agglomerate was withdrawn from the reactor at a rate of 200 lb/h.
• the productivity of the catalyst was 98 pounds of polyethylene per pound of prepolymer which corresponds to an activity of 210 grams polyethylene per millimole titanium per hour per bar of ethylene partial pressure.
• the Unear polyethylene had a density of 0.908 and a melt index MI 2 .i 6 , 1 2 , of 0.4 dg/min.
• the Melt Flow Ratio, I21/I 2 was 28 and the ether extractables were 1.9 % by weight.
• Example 1 The process of Example 1 is foUowed with the exception that the Ziegler- Natta catalyst is directly injected into the reactor without having been converted to prepolymer. A Unear polyethylene is obtained.
• Example 1 The process of Example 1 is foUowed with the exception that the external electron donor utilized is as foUows:
• Example 9 diethyl ether, Example 10 dibutyl ether,
• Example 11 dioctyl ether, Example 12 tert-butyl methyl ether.

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• 1999
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