JPH0912626A - Catalyst system and method of polymerization of olefin in the presence of the system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a highly active catalyst system by combining a specified catalyst solid with a specified organometallic compound and an electron donor.

SOLUTION: This catalyst system for olefin polymerization comprises (A) a catalyst solid obtained by mixing an Mg compound such as magnesium oxide with a transition metal compound of e.g. the formula: MY_x(O-R')_1-x (wherein M is a transition metal of group IV or VB in the periodic table; Y is a halogen or the like; R' is an alkyl, an aryl or the like; 0≤x≤t; and (t) is the valence of M), reducing and halogenating the obtained mixture with a reducing and halogenating agent containing a complex of the empirical formula: Ar.M'X'₂Al₂ X''₆ (wherein M'' is a transition metal of group IV in the periodic table; Ar is an aromatic hydrocarbon group; and X' and X'' are each a halogen) and separating the coprecipitated catalyst solid from the obtained reaction mixture, (B), an organometallic compound containing a metal of group IA, IIA, IIB, IIIA or IVA in the periodic table and (C) at least one electron donor.

COPYRIGHT: (C)1997,JPO

Description

Detailed Description of the Invention

[0001]

The present invention relates to a catalyst system comprising a magnesium compound and a catalytic solid based on at least one transition metal compound and an organometallic compound (cocatalyst). The invention additionally relates to the use of said catalyst system for the polymerization of olefins, typically ethylene.

[0002]

The patent application EP 0 574 067 discloses a catalytic solid for the polymerization of olefins, a process for obtaining the solid, and its use for the polymerization of olefins, especially ethylene. The catalyst solid comprises a coprecipitate of magnesium halide and at least one transition metal halide. The coprecipitate comprises a magnesium compound such as magnesium chloride or magnesium alcoholate, a compound of formula MY
_x (OR ′) _tx or M′O _y (OR ″) _s-2y 1
A mixture of compounds of formula ( _II ) and treatment of the resulting mixture with a complex of formula M ″ (A) Al ₂ (X ′, X ″) ₈ 'Or X'represents halogen, M and M'represent group IVB and VB transition metals, M "represents group IVB transition metal, A represents aromatic hydrocarbon, Y represents halogen or ( O-
R ″ ′) group, R ′, R ″ and R ″ ″ represent an optionally substituted alkyl, aryl or cycloalkyl group, 0 ≦ n ≦ 2, 0 ≦ x ≦ t, t is M Equal to the valence, and 0 ≦ y ≦ s / 2, where s equals the valence of M).
However, the disadvantage of the solid is, on the one hand, the relatively low activity of its catalytic solid, and on the other hand, the relatively low apparent specific weight of the polymer obtained. The polyethylene obtained in the presence of this known catalytic solid has a high content of oligomers responsible for smoke emission during subsequent processing of the polyethylene, for example in bottle blow molding processes. In addition, the oligomers present destroy the mechanical and rheological properties of the polyolefin.

[0003]

The object of the present invention is to propose a catalyst system having a high activity.

[0004]

To achieve this object, the present invention comprises: a) a magnesium halide and at least one IV of the periodic table
A catalytic solid based on a coprecipitate of a Group B and VB transition metal halide, i) one of which is Mg oxide and the formula MgX _n (OR)
_At least one magnesium compound selected from the compounds of _2-n , and at least one compound selected from the compounds of the formulas MY _x (OR ′) _tx and M′O _y (OR ″) _s-2y , on the other hand (Wherein X represents halogen, M and M'represent transition metals of Group IVB and VB of the periodic table, the valence of which is at least 4 and Y is halogen). Or represents an (O—R ″ ″) group,
Each of R, R ′, R ″ and R ″ ″ represents an optionally substituted alkyl, aryl or cycloalkyl group, and 0 ≦ n ≦ 2, 0 ≦ x ≦ t and t are equal to the valence of M. , 0 ≦ y ≦ s / 2, where s is equal to the valence of M ′. ), Ii) The mixture thus obtained is replaced by the empirical formula Ar.
M ″ X ′ ₂ Al ₂ X ″ ₆ (wherein M ″ represents a transition metal of Group IVB of the periodic table, Ar represents an aromatic hydrocarbon, and X ′ and X ″ each represent halogen). At least 1
A catalyst solid obtained by reducing and halogenating with a reducing and halogenating agent comprising a complex of a species, and iii) separating the coprecipitated catalyst solid thus obtained from the reaction mixture, and b) the IA of the Periodic Table. , IIA, IIB, IIIA and IVA, organometallic compounds (cocatalysts) of metals, and c) a catalyst system comprising at least one electron donor is proposed.

[0005]

One advantage of this catalyst system is that the activity of the catalyst system is higher than that of known catalysts. In fact, the use of an electron donor in combination with the catalytic solid and the cocatalyst can have the advantage of increased activity with respect to the activity of catalyst systems in the art. The polymers obtained via this catalyst system have in particular a low oligomer content. The reduced content of low apparent specific weight components is
Guarantees improved mechanical and rheological properties. Smoke emission is reduced during subsequent processing of the resulting polymer, for example in bottle blow molding processes. The catalyst solvent employed in the catalyst system of the present invention is preferably the patent application EP 0 57
The method described in 4067 is followed. The characteristics of the process for producing this solid and some possible forms are discussed in detail in the above mentioned documents and are incorporated by reference in the present patent application, in particular page 2, column 2, line 19 to 5
It is described on page 8, column 29 line. According to one particular form, a reducing and halogenating agent supported on an inorganic support is employed to obtain the catalytic solid. This support can be selected from metal halides such as magnesium chloride and metal oxides. Well suited oxides are oxides of silicon, aluminum, titanium, zirconium and thorium, mixtures thereof and mixed oxides of these metals. Silica is preferably adopted. Dehydroxy silica is a good choice.

The catalyst system of the present invention also contemplates the use of organometallic compounds which act as activators of the solid catalyst complex, which are commonly referred to as "cocatalysts". It can be selected from organometallic compounds of lithium, magnesium, zinc, aluminum or tin. Best results are obtained with organoaluminum compounds. As an organometallic compound,
Adopting fully alkylated compounds in which the alkyl chain contains up to 20 carbon atoms and is linear or branched, for example n-butyllithium, diethylmagnesium, diethylzinc, tetraethyltin, tetrabutyltin and trialkylaluminium. You can It is also possible to employ alkyl metal hydrides whose alkyl groups contain up to 20 carbon atoms, for example diisobutylaluminum hydride and trimethyltin hydride. Metal alkyl halides in which the alkyl group contains up to 20 carbon atoms are also suitable, for example ethylaluminum sesquichloride, diethylaluminium chloride and diisobutylaluminium chloride. It is also possible to employ an organometallic compound obtained by reacting a trialkylaluminum having a group of up to 20 carbon atoms or a dialkylaluminum hydride with a diolefin containing 4 to 20 carbon atoms, particularly iso- It is a compound called prenylaluminum. In general, trialkylaluminums are preferred, especially those in which the alkyl chain is straight-chain and contains up to 18 carbon atoms and further contains from 2 to 8 carbon atoms. Triethyl aluminum and triisobutyl aluminum are preferred.

According to a first advantageous embodiment, the electron donor comprises at least one organic compound containing one or more atoms having one or more pairs of free electrons or one or more atomic groups. The atom or group of atoms having one or more pairs of free electrons includes oxygen, nitrogen, sulfur or groups containing one of such elements. Examples of electron donors that can be preferably used in this catalyst system are alcohols, phenols, ethers, ketones, aldehydes, organic acids, organic acid esters, organic acid halides, organic acid amides, amines, alkoxys. Silane and nitrile. Alcohols and phenols which can be used are those containing up to 18 carbon atoms, for example methyl alcohol, n-butyl alcohol, cyclohexyl alcohol, stearyl alcohol and phenol. Examples of ethers which may be mentioned are those containing 2 to 20 carbon atoms, for example isoamyl ether. Commonly used ketones are those containing from 3 to 18 carbon atoms, such as methyl ethyl ketone and acetophenone. Commonly used aldehydes are those containing from 2 to 15 carbon atoms, such as octyl aldehyde and benzaldehyde.

Examples of organic acids are those containing up to 24 carbon atoms, such as butyric acid and anisic acid. Organic acid esters that can be used include, for example, methyl acetate, ethyl propionate, methyl butyrate, propyl methacrylate, ethyl benzoate, phenyl benzoate,
Ethyl o-methoxybenzoate, methyl p-toluate,
It contains 2 carbon atoms such as methyl salicylate, ethyl naphthoate, ethyl or butyl phthalate and anisate.
-30 are included. Particularly suitable are ethylbenzoate, octadecyl 3,5-bis (1,1-dimethylethyl) -4-hydroxybenzenepropanoate and dibutylphthalate. Examples of organic acid halides which may be mentioned are those containing 2 to 15 carbon atoms, for example acetyl chloride and toluoyl chloride.

Acid amides which may be mentioned are, for example, acetamide, benzamide and toluamide. Amines which can be used are, for example, diethylamine, piperidine, tribenzylamine, aniline and pyridine. Nitriles which can be used are, for example, acetonitrile and benzonitrile. Alkoxysilanes that can be used are tetraethoxysilane and dimethyldioxysilane. Alcohols, ethers, organic acid esters and alkoxysilanes are suitable. Organic acid esters are preferred, especially esters of aromatic organic acids, especially dibutyl phthalate, more preferably ethyl benzoate. According to another preferred embodiment, the amount of electron donor used is usually such that the molar ratio of the amount of organometallic compound used to the amount of electron donor used is at least 0.0.
1 and more precisely at least 0.05, at least
A value of 0.2 is most advantageous. Most often, the ratio of these amounts does not exceed 100, preferably does not exceed 80, values of 60 or less being most recommended.

The present invention also proposes a process for polymerizing olefins, which is characterized in that at least one olefin is contacted with the catalyst system described above. The process of the invention has the advantage of reducing the oligomer content of the resulting polyolefin. The use of the catalyst system in this polymerization process can increase the activity of the catalyst system while increasing the apparent specific weight of the resulting polymer.
The polymerization is carried out by contacting at least one olefin with the catalyst system, which comprises a catalyst solid, an organometallic compound and an electron donor. The catalytic solid used is preferably free of electron donors. A preferred practice of the process of the present invention is the continuous or simultaneous use of the components of the catalyst system in the polymerization mixture.

First, in a particularly preferred form, the electron donor can be introduced separately into the polymerization environment at any time, preferably at the beginning of the polymerization. Second, in a particularly advantageous form, the electron donor is mixed with the organometallic compound and introduced into the polymerization environment, the mixture being prepared beforehand.
This mixture can be obtained by simply contacting the electron donor with an organometallic compound, or by adding the electron donor, preferably slowly, to a solution of the organometallic compound, or adding a solution of the electron donor to a solution of the organometallic compound. It can be obtained by adding It is preferred to add the electron donor in its pure state to the solution of the organometallic compound in a solvent such as liquid aliphatic, cycloaliphatic and aromatic hydrocarbons. Preferred solvents are hydrocarbons containing up to 20 carbon atoms, especially linear alkanes (eg n-butane,
n-hexane and n-heptane) or branched alkanes (eg isobutane, isopentane or isooctane)
Or cycloalkanes (eg cyclopentane and cyclohexane). Good results are obtained with linear alkanes. Hexane is preferred.

The total amount of organometallic compound used in the polymerization process can vary within wide limits. It is generally from 0.02 to 50 per liter of solvent or diluent or reactor volume.
Millimoles, preferably 0.2-2 per liter.
5 mmol. The olefins to be polymerized are olefins containing 2 to 20 carbon atoms, preferably 2 to 6 carbon atoms, such as ethylene, propylene, 1-butene, 4,
It can be chosen from -methyl-1-pentene and 1-hexene. Ethylene, 1-butene and 1-hexene are suitable. Ethylene is particularly preferred. Of course, in order to obtain a copolymer, one may find, for example, a mixture of two of the above-mentioned olefins or a mixture of one or more of these olefins with one or more diolefins preferably containing from 4 to 20 carbon atoms. These various olefins can be used simultaneously. These diolefins are 1,
Non-conjugated aliphatic diolefins such as 4-hexadiene, 4-
Vinylcyclohexene, 1,3-divinylcyclohexane,
It may be a monocyclic diolefin such as cyclopentadiene or 1,5-cyclooctadiene, an alicyclic diolefin having an endocyclic bridge such as dicyclopentadiene or norbornadiene, and a conjugated aliphatic diolefin such as butadiene and isoprene.

This process also applies particularly well to the preparation of homopolymers of ethylene and of copolymers containing at least 90 mol%, preferably at least 95 mol% ethylene. Preferred comonomers of ethylene are propylene, 1-butene, 1-hexene, 1-octene and
1,5-hexadiene and mixtures thereof. Highly preferred comonomers are 1-butene, 1-hexene and mixtures thereof. The polymerization process may be carried out by any of the known methods in a solution of the solvent which is the olefin itself in the liquid state, or in suspension in a hydrocarbon diluent, or else in the gas phase. Gas phase polymerization is considered as one embodiment. In gas phase polymerization, a gas stream containing at least one olefin is contacted with the catalyst system in a fluidized bed. As a result, the flow rate of the gas stream must be sufficient to maintain the flow of the polyolefin, which depends on the rate of formation of the polyolefin and the rate at which the catalyst system is consumed. The total partial pressure of the olefin (olefins) may be below or above atmospheric pressure, with preferred partial pressures varying from atmospheric pressure to about 7 MPa. Pressures of 0.2-5 MPa are generally suitable. The choice of temperature is not important. The temperature is generally 30 to 200 ° C. The diluent gas must be inert to the polyolefin and can be used at will.

Polymerization has been found to be particularly advantageous in gas phase polymerization processes which are generally characterized by a limited heat transfer capacity. This is because the dynamic properties of the solid catalyst complex show a clear induction period. The polymerization process can optionally be carried out in the presence of a molecular weight regulator such as hydrogen. The polymerization process can be carried out continuously or discontinuously in a single reactor or in several reactors arranged in series, the polymerization conditions in one reactor (temperature, The optional comonomer content, optional hydrogen content, type of polymerization medium) may differ from the conditions employed in other reactors.

The examples described below are used to illustrate the invention. In these examples catalytic solids were prepared and subsequently used for the polymerization of ethylene in the gas phase. The meaning of the symbols used in these examples, the units expressing the stated amounts and the methods for measuring these amounts are given below. Act = catalytic activity represented by g number of insoluble polyolefin obtained by dividing g number of insoluble polyolefin obtained per 1 g of catalyst per hour by the partial pressure of ethylene. SD = kg / m ³ measured according to ASTM standard D 1928
The standard density of the polymer, expressed as ASW = k measured by free flow according to the following procedure
Apparent specific weight of the polymer powder, expressed in g / m ³ : The powder to be analyzed, excluding its packaging, is placed in a 50 cm ³ volume cylindrical container, the lower end being 20 mm above the upper end of the container. Drain from the hopper. Then weigh the container filled with powder,
The tare is subtracted from the recorded weight and the result obtained (expressed in g) is multiplied by 20,000.

S = oligomeric fraction of the polymer,
Expressed in g of oligomers per kilogram of polymer, measured by extraction with hexane at the temperature of its boiling point. Measured by velocity gradient per second at μ0 = 190 ℃, dPa
Kinematic viscosity expressed in s. μ1 = 190 ° C, measured by velocity gradient per 10 seconds, d
Kinematic viscosity expressed in Pa s. μ2 = 190 ° C., measured with a velocity gradient per 100 seconds,
Kinematic viscosity expressed in dPa s. MI2 = melt index of the polymer at 190 ° C.,
Measured under ASTM standard D 1238 (1990) under 2.16 kg load and expressed in g / 10 min. HLMI = melt index of the polymer at 190 ° C., measured in g / min according to ASTM standard D 1238 (1990) under a load of 21.6 kg.

Example 1 (reference) A. Preparation of catalyst solid (1) Compounds Mg (O-R) ₂ and Ti (O-R ') ₄
Preparation of a mixture of 531 mmol of titanium tetrabutyrate and 1309 mmol of magnesium diethylate were introduced into a 1 liter reactor equipped with a stirrer. The temperature is then 140 ° C
And the contents were stirred for 4 hours, maintaining the temperature at 140 ° C. until the magnesium diethylate was completely dissolved. The solution thus obtained was further stirred at 140 ° C. for 1 hour. The solution was then diluted with hexane to give a final titanium concentration of 18.8 g / liter and a magnesium concentration of 24.8 g / liter. (2) Preparation of reduction and halogenated complex 113 mmol of aluminum trichloride and 389 mmol of aluminum metal powder were provided with a stirrer.
It was introduced into a 250 ml reactor. 125 contents of the reactor
Mix at 4 ° C for 4 hours. After cooling to ambient temperature 80 ml of toluene were added. A solution consisting of 6 ml of titanium tetrachloride and 20 ml of toluene was then added at a temperature of 125
The suspension was added drop wise while being maintained at ° C. The suspension was then kept stirring at 125 ° C. for 4 hours. The contents of the reaction vessel were then cooled to ambient temperature.

(3) Impregnation of the inorganic oxide with a reducing and halogenating agent complex, and reduction and halogenation of the mixture from step (1) 4 g of silica (Grace SD SD3216-30, 16 hours in a fluidized bed furnace, (Fired at 815 ° C with nitrogen nitrogen) and 50 ml of toluene, equipped with a stirrer 25
It was introduced into a 0 ml reactor. 10 ml of the solution obtained in (2) was added to this suspension. After standing, the supernatant was removed and the reduced and halogenated complex impregnated silica was resuspended in 100 ml of hexane. 13.1 ml of the mixture obtained in (1) was then added and the whole was stirred at 70 ° C. for 35 minutes. The solid was collected, washed twice with hexane and resuspended in 60 ml hexane. Then add 3 ml of titanium tetrachloride,
The suspension was stirred at 60 ° C. for 15 minutes. Collect the catalyst solids,
It was washed twice with hexane and dried under reduced pressure.

B. Polymerization of ethylene 2 mmol triethylaluminum (promoter) and 1
00 ml of isobutane was introduced into a 3 liter autoclave at ambient temperature. The temperature was 85 ° C. After that, 0.25MP
Hydrogen with a partial pressure of a, ethylene with a partial pressure of 0.6 MPa and 245 mg of the catalyst solid obtained in A were introduced therein. The temperature and the partial pressure of ethylene were maintained for 120 minutes, and the supply of ethylene was stopped. After degassing and cooling the polymerization mixture to ambient temperature, 18
0 g of polyethylene (Act = 61) was collected, which showed the following properties: SD = 963.1, ASW = 320, S = 7.
5, μ1 = 22300, μ2 = 10000, MI2 = 3, HLMI = 10
7, μ0 / μ2 = 3.4.

Example 2 (according to the invention) The polymerization was carried out with the catalytic solid of Example 1 with the following modifications.
Was carried out as described in: Atmer® 1 which is a commercial electron donor (ED).
TE of 63 (Atmer 163) and triethyl aluminum (TEAL)
Premixing with an AL / ED molar ratio of 6—amount of catalyst solid used: 244 mg. 345 g of polyethylene (Act = 118) was obtained with the following properties: SD
= 961.2, S = 4.1, μ1 = 46500, μ2 = 17500, MI
2 = 0.87, HLMI = 29, μ0 / μ2 = 4.55, particle size distribution: average diameter = 632 μm, standard deviation = 398 μm.

Example 3 (according to the invention) The polymerization was carried out as in Example 2 with the following modifications. Premixing of vinyltrimethoxysilane as electron donor with triethylaluminum in a triethylaluminum / vinyltrimethoxysilane molar ratio of 10; amount of catalyst solid used: 166 mg. 233 g of polyethylene (Act = 117) was obtained with the following characteristics: SD
= 960.6, ASW = 362, S = 3.6, μ1 = 37400, μ2
= 16100, MI2 = 1.37, HLMI = 37, μ0 / μ2 = 3.57, Particle size distribution: mean diameter = 571 μm, standard deviation = 274 μm.

Example 4 (according to the invention) The polymerization was carried out as described in Example 2 with the following modifications. Premixing of vinyltrimethoxysilane as electron donor with triethylaluminum in a triethylaluminum / vinyltrimethoxysilane molar ratio of 5; amount of catalyst solid used: 232 mg. 480 g of polyethylene (Act = 172) was obtained. Example 5 (according to the invention) The polymerization was carried out as described in Example 2 with the following modifications. Premixing of n-butyldiethanolamine as electron donor and triethylaluminum in a molar ratio of triethylaluminum / n-butyldiethanolamine of 6; amount of catalyst solid used: 221 mg. 350 g of polyethylene (Act = 132) was obtained.

Claims (12)

[Claims] 1. A) magnesium halide and at least 1
Catalytic solids based on coprecipitates of halides of transition metals of group IVB and VB of the periodic table of species selected from i) Mg oxide and compounds of formula MgX _n (OR) _2-n At least one magnesium compound and the formula MY _x (O-
R ′) _tx and M′O _y (OR ″) _s-2y are mixed with at least one transition metal compound (wherein X represents halogen and each of M and M ′ is Represents a transition metal of Group IVB and Group VB of the Periodic Table, the valence of which is at least 4, Y represents a halogen or a (O—R ″ ″) group, and R, R ′, R ″ and R ″ Each represents an optionally substituted alkyl, aryl or cycloalkyl group, 0 ≦ n ≦ 2, 0 ≦ x ≦ t, t is equal to the valence of M, 0 ≦ y ≦ s / 2, s is M ′), Ii) the mixture so obtained is empirically represented by Ar ·
M ″ X ′ ₂ Al ₂ X ″ ₆ (wherein M ″ represents a transition metal of Group IVB of the periodic table, Ar represents an aromatic hydrocarbon, and X ′ and X ″ each represent halogen). At least 1
A catalyst solid obtained by reducing and halogenating with a reducing and halogenating agent comprising a complex of a species, and iii) separating the coprecipitated catalyst solid thus obtained from the reaction mixture, and b) the IA of the Periodic Table. , IIA, IIB, IIIA and IVA, a catalyst system comprising an organometallic compound of a metal, the solid catalyst system further comprising c) at least one electron donor. 2. A catalyst system according to claim 1, characterized in that the electron donor comprises an organic compound containing one or more atoms or one or more atomic groups with one or more pairs of free electrons. 3. The electron donor is an alcohol, a phenol, an ether, a ketone, an aldehyde, an organic acid,
Catalyst system according to claim 2, characterized in that it is selected from organic acid esters, organic acid halides, organic acid amides, amines, alkoxysilanes and nitriles. 4. The catalyst system according to claim 2, wherein the electron donor comprises ethyl benzoate. 5. The catalyst system according to claim 1, wherein the molar ratio of the organometallic compound to the electron donor is 0.01 to 100. 6. Catalytic system according to claim 1, characterized in that the reducing and halogenating agent is supported on an inorganic support, preferably silica. 7. An at least one olefin.
7. A method for polymerizing an olefin, which comprises contacting the catalyst system according to any one of 1 to 6. 8. Process according to claim 7, characterized in that the components of the catalyst system are introduced into the polymerization mixture either continuously or simultaneously. 9. The method according to claim 7, wherein the electron donor is mixed with the organometallic compound and introduced into the polymerization environment, and the mixture is prepared in advance. 10. Process according to claim 7, characterized in that the olefin is selected from ethylene, 1-butene and 1-hexene. 11. Process according to claim 7, characterized in that the polymerization is carried out in the gas phase. 12. The process according to claim 7, wherein the catalytic solid used is free of electron donors.