EP0436672A1 - Catalyseur de ziegler a support d'oxide de magnesium modifie par de l'acide et de l'alcanol superieur, et procede de preparation de polyethylene a haute densite a repartition etroite de la masse moleculaire - Google Patents

Catalyseur de ziegler a support d'oxide de magnesium modifie par de l'acide et de l'alcanol superieur, et procede de preparation de polyethylene a haute densite a repartition etroite de la masse moleculaire

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Publication number
EP0436672A1
EP0436672A1 EP19900901100 EP90901100A EP0436672A1 EP 0436672 A1 EP0436672 A1 EP 0436672A1 EP 19900901100 EP19900901100 EP 19900901100 EP 90901100 A EP90901100 A EP 90901100A EP 0436672 A1 EP0436672 A1 EP 0436672A1
Authority
EP
European Patent Office
Prior art keywords
acid
catalyst
carboxylic acid
magnesium oxide
alkanol
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19900901100
Other languages
German (de)
English (en)
Inventor
John Tai-Tung Hsieh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ExxonMobil Oil Corp
Original Assignee
Mobil Oil Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mobil Oil Corp filed Critical Mobil Oil Corp
Publication of EP0436672A1 publication Critical patent/EP0436672A1/fr
Withdrawn legal-status Critical Current

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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
    • C08F10/02—Ethene

Definitions

  • High density ethylene homopolymers and copolymers (HDPE) with higher olefins are widely used in injection molding operations.
  • Advantageously such resins should have a narrow molecular weight distribution (MWD) which is largely determined by the nature of the catalyst.
  • the catalyst should also exhibit other desirable characteristics for commercial use. For example, the productivity of the catalyst should be as high as possible so that the resin will have a high ratio of polymer to catalyst residue. It is also very desirable that the catalyst result in a polymer having a large particle size, an advantage vrtiich is particularly sought in gas-phase polymerization. Another desirable characteristic of the catalyst is that it have a hydrogen response.
  • a high hydrogen response means that small increases in the amount of hydrogen used in the reactor (to control molecular weight in the known manner) will result in substantial decrease in molecular weight and a higher melt index polymer.
  • the need for excessive amounts of hydrogen decreases the reactor volume available for the ethylene and other comonomers, thereby reducing productivity.
  • My U.S. Patent 4,167,493 discloses the treatment of magnesium oxide with methanol, a Lewis base, prior to impregnation with a titanium compound and an aluminum compound to form a Ziegler catalyst vrtiich produces high density polyethylene with a narrow MWD suitable for injection molding.
  • a MgO supported catalyst is treated with an organic acid (a Lewis acid), then with the product of TiCl, and a higher alkanol, and finally with an organoaluminum compound as a reducing agent.
  • the catalyst is particularly suitable for preparing HDPE with narrow MWD and large particle size, excellent productivity and hydrogen response.
  • Magnesium oxide is treated with an organic acid, then with the product of 0.5 to 1.5 moles of an alkanol and one mole of
  • the catalyst is used in the polymerization of ethylene polymers and copolymers, particularly HDPE, having narrow MWD and large particle size.
  • the initial treatment of the MgO support with the organic acid is conducted with a molar excess of MgO.
  • the ratio of the organic acid to MgO is from 0.001 to 0.5, most preferably from 0.005 to 0.1.
  • the organic acid is desirably an aliphatic mono-carboxylic acid, an aromatic mono-carboxylic acid, an aliphatic dicarboxylic acid, or an aromatic dicarboxylic acid.
  • Suitable aliphatic mono-carboxylic acids have the formula R-C00H, vrtierein R is H, an alkyl group of 1 to 17 carbon atoms, or a substituted alkyl group of 1 to 17 carbon atoms, such as formic, acetic, propionic, butyric, valeric, caproic, caprylic, capric, lauric, myristic, palmitic or stearic acid, preferably formic, acetic or propionic acid, and most preferably acetic acid.
  • Suitable aromatic mono-carboxylic acids are benzoic and alkyl- or alkoxy-substituted benzoic acids, such as o-toluic, m-toluic, p-toluic, o-methoxybenzoic, m-methoxybenzoic, p-methoxybenzoic, o-ethoxybenzoic, m-ethoxybenzoic or p-ethoxybenzoic acids (the latter three also known as 1-, 2- or 3-ethoxybenzoic acids, respectively), preferably o-ethoxybenzoic, p-ethoxybenzoic or m-ethoxybenzoic, and most preferably p-ethoxybenzoic acid.
  • benzoic and alkyl- or alkoxy-substituted benzoic acids such as o-toluic, m-toluic, p-toluic, o-methoxybenzoic, m-methoxybenzoic,
  • Suitable aliphatic dicarboxylic acids are oxalic, malonic, succinic, glutaric, adipic, maleic and fu aric acids.
  • Suitable aromatic dicarboxylic acids are phthalic, isophthalic and terephthalic acids.
  • the acid is typically dissolved in an inert organic solvent, such as hexane, in which the MgO is refluxed.
  • an inert organic solvent such as hexane
  • the acid-treated MgO support is again treated in a similar manner with the product of an alkanol or polyhydroxy alkanol having 5 to 12 carbon atoms and TiCl. in a ratio of 0.5 to 1.5, preferably 0.8 to 1.2, moles of the alkanol per mole of TiCl 4 .
  • the treated MgO-based catalyst precursor is activated with an organoaluminum compound in the known manner.
  • Particularly suitable aluminum compounds have the formula R n A "*" X (3-n) n w ⁇ cn R * s alkyl, alkenyl, alkylaryl or arylalkyl having 1 to 20 carbon atoms, X is hydrogen or halogen and n is 1, 2 or 3.
  • R alkyl of 1 to 6 carbon atoms are preferred.
  • Ethylene can be homopolymerized or copolymerized with higher olefins using the catalysts prepared according to the present invention, by any suitable process. Such processes include polymerizations carried out in suspension, in solution or in the gas phase. Gas phase polymerization reactions are preferred, such as those conducted in stirred bed reactors and, especially, fluidized bed reactors.
  • the molecular weight of the polymer is controlled in the known manner, by using hydrogen.
  • molecular weight may be suitably controlled with hydrogen when the polymerization is carried out at relatively low temperatures, e.g., from 30 to 105°C. This control of molecular weight may be evidenced by a measurable positive change in melt index (I 2 ) of the polymer produced.
  • the molecular weight distribution (MWD) of the polymers prepared with the catalysts of this invention, as expressed by the melt flow ratio (MFR) values ( ⁇ j / ⁇ )* varies from about 20 to about 32, preferably 21 to 29, for HDPE products with a density of 0.940 to 0.965 g/cc.
  • MFR values are indicative of a relatively narrow molecular weight distribution of the polymer.
  • MFR values are indicative of the polymers especially suitable for injection molding applications since the polymers having such MFR values exhibit relatively low amounts of warpage and shrinkage on cooling of the injection molded products.
  • the catalysts prepared according to the present invention are highly active and typically have activity of 1,000-5,000 grams of polymer per gram of catalyst per 830 kPa (120 psi) of ethylene per hour.
  • the linear polyethylene polymers prepared in accordance with the present invention may be homopolymers of ethylene or copoly ers of ethylene with one or more C,-C,Q alpha-olefins.
  • copolymers having two monomeric units are possible as well as terpolymers having three monomeric units.
  • polymers include ethylene/1-butene copolymers, ethylene/1-hexene copolymers, etylene/1-octene copolymers, ethylene/4-methyl-1-pentene copolymers, ethylene/1-butene/l-hexene terpolymers, ethylene/propylene/1-hexene terpolymers and ethylene/propylene/1-butene terpolymers.
  • propylene is employed as a comonomer
  • the resulting linear low density polyethylene polymer preferably has at least one other alpha-olefin comonomer having at least four carbon atoms in an amount of at least 1 percent by weight of the polymer.
  • a commercially significant advantage of the catalysts of this invention is that of producing polymer particles of a relatively large size over 200 microns and usually over 300 microns.
  • a particularly desirable method for producing polyethylene polymers and copolymers according to the present invention is in a fluid bed reactor. Such a reactor and means for operating it are described by Levine et al, U.S. Patent No. 4,011,382, Karol et al, U.S. Patent No. 4,302,566, and by Nowlin et al, U.S. Patent 4,481,301.
  • EXAMPLE 1 (Use of an Aliphatic Carboxylic Acid in Catalyst Synthesis) A sample of MgO support (Merc -Maglite D) was dried in a 500-ml 3-neck flask under nitrogen at 250°C for 16 hours without stirring. 30.8 grams of this dry MgO support was then slurried in 200 ml of dry hexane in a 500-ml 3-neck flask and refluxed for 16 hours with 0.44 ml glacial acetic acid (99.81 pure acetic acid) at 0.01 molar ratio of the acid to the MgO.
  • MgO support Mer -Maglite D
  • a dilute pentanol solution was prepared by adding 53.5 ml of pre-dried 1-pentanol (0.494 mole) to 45 ml of dry hexane in another flask. To avoid a rapid isotherm, 54.4 ml of neat TiCl 4 (0.494 mole) was added dropwise to the 1-pentanol solution to form the titanium compound solution. The (1:1 pentanol/TiCl 4 ) solution was immediately added to the acetic acid-treated O at room temperature. The slurry was refluxed at 70°C for 16 hours and allowed to cool.
  • the catalyst precursor was washed 6 times with 100 ml of dry hexane.
  • the solid was re-slurried with 200 ml of dry hexane, and 12 ml of 25 wt. % tri-n-hexylaluminum (TNHAL) solution (7.66 mmole TNHAL) was slowly added (3 minutes) to form a catalyst having an Al/Ti ratio of 0.23.
  • TNHAL tri-n-hexylaluminum
  • the catalyst was dried for 16 hours at 65°C under nitrogen purge, to give a free-flow light brown powder. Elemental analysis indicated that the finished catalyst contained 1.1 mmoles/g of Ti.
  • a dilute pentanol solution was prepared by adding 11.8 ml of pre-dried 1-pentanol (0.109 mole) to 10 ml of dry hexane in another flask. To avoid a rapid isotherm, 12 ml of neat TiCl. (0.109 mole) was added dropwise to the 1-pentanol solution to form the titanium compound solution. The (1:1 pentanol/TiCl.) solution was immediately added to the 2-EBA treated gO at room temperature. The slurry was refluxed at 7C C for 16 hours and allowed to cool. The catalyst precursor was washed six times with 60 ml of dry hexane.
  • the solid was re-slurried with 60ml of dry hexane, and 2.64 ml of 26 wtt tri-n-hexylaluminum (TNHAL) solution (1.636 mmole TNHAL) was slowly added (about three minutes) to form a catalyst having an Al/Ti ratio of 0.25.
  • TNHAL tri-n-hexylaluminum
  • the catalyst was dried for 16 hours at 70°C under nitrogen purge, to give a free-flow dark brown powder. Elemental analysis indicated that 1.34 mmoles/g of Ti was on the finished catalyst.
  • Example 4 Slurry Polymerization With Example 2 Catalyst A one gallon slurry reactor was purged with nitrogen at 90°C overnight, cooled to room temperature, 1.8 cc of 25 weight I of di-isobutylaluminumhydride-heptane solution was injected into the reactor, and 0.42 gram of the catalyst of Example 2 was transferred to the reactor with 2 liters of hexane. While stirring, the reactor was heated to 90°C, maintained at 90°C, and 5 cc 1-hexene and 930 kPa (135 psi) partial pressure of hydrogen were added to the reactor.
  • Ethylene was fed continuously to the reactor to maintain the ethylene partial pressure at 930 kPa (135 psi) for 80 min.
  • the product was stabilized with 8.5 cc Irganox 1076 solution (500 ppm in hexane) and dried in a vacuum oven for 4 hours.
  • the product was 335 grams of large mean-particle-size (greater than 400 microns), 10.9 I 2 , 272 I 21 , 25 MFR and 0.962 (g/cc) density polymer.
  • EXAMPLE 6 (Slurry Polymerization) In a manner similar to that of Example 5 polymerization was conducted using the catalyst of Example 2 to determine the effect of the catalyst on median particle size of the polymer and the hydrogen response of the catalyst. The polymerization used a 1:1 molar ratio of hydrogen to ethylene. Results are reported in Table 2 which shows that the catalyst of Example 2 made with pentanol gives a high hydrogen response and a large median particle size, both of which are desirable. TABLE 2
  • Example 2 the catalyst of Example 1 was used to copolymerize ethylene with 1-hexene, in the manner similar to that of Example 6.
  • the polymerization was conducted in an 8 liter (2 gallon) slurry reactor at 90°C, with 4 liters of polymerization grade hexane. Approximately 0.07 g of the Example 1 catalyst (0.078 mmole Ti) and 3.6 ml of di-isobutylaluminumhydride solution (25 wt. ⁇ in heptane; 4.53 mmole Al), 10 ml of 1-hexene comonomer, and hydrogen were added in this order to the reactor. The polymerization was run at an ethylene partial pressure of 931 kPa (135 psia) to produce the HPDE products. The H- : C molar ratio was maintained at 1:1.
  • the data of Table I indicates that the hydrogen response of the Examples 1 and 2 catalysts (i.e., the melt index of the polymer made with the catalyst at a given H 2 :C 2 molar ratio) and the MFR's of the polymer products produced with the two catalysts are comparable.
  • the activity of the Example 1 catalyst, prepared on the acetic acid - modified MgO support is substantially higher than that of the Example 2 catalyst, prepared on the 2-ethoxybenzoic acid-modified MgO support.

Abstract

On utilise du MgO traité à l'acide carboxylique, par exemple, à l'acide acétique, comme support pour un catalyseur de Ziegler Al-Ti dans lequel le composant Ti est le produit d'un alcanol contenant 5 à 12 atomes de carbone et de TiCl4 afin de produire un polyéthylène à haute densité (PEHD) présentant une répartition étroite de la masse moléculaire (RMM) ainsi qu'une grande taille de particule permettant le moulage par injection.
EP19900901100 1989-08-03 1989-08-30 Catalyseur de ziegler a support d'oxide de magnesium modifie par de l'acide et de l'alcanol superieur, et procede de preparation de polyethylene a haute densite a repartition etroite de la masse moleculaire Withdrawn EP0436672A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US38920489A 1989-08-03 1989-08-03
US389204 1989-08-03

Publications (1)

Publication Number Publication Date
EP0436672A1 true EP0436672A1 (fr) 1991-07-17

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Country Status (4)

Country Link
EP (1) EP0436672A1 (fr)
JP (1) JPH04500830A (fr)
AU (1) AU4743090A (fr)
WO (1) WO1991002009A1 (fr)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5583085A (en) * 1994-06-13 1996-12-10 W. R. Grace & Co.-Conn. Preparation of dehydroxylated supports

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Publication number Priority date Publication date Assignee Title
GB1553673A (en) * 1975-07-30 1979-09-26 Bp Chem Int Ltd Polymerisation catalyst
JPS5441985A (en) * 1977-09-09 1979-04-03 Mitsui Petrochem Ind Ltd Polymerization or copolymerization of olefin

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9102009A1 *

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AU4743090A (en) 1991-03-11
WO1991002009A1 (fr) 1991-02-21
JPH04500830A (ja) 1992-02-13

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