Components and catalysts for the polymerization of olefins

ES 2 297 014 T3

DESCRIPTION

Components and catalysts for olefin polymerization.

The present invention relates to catalyst components for the polymerization of olefins, to the catalyst obtained therefrom and to the use of said catalysts in the polymerization of olefins CH₂= CHR where R is hydrogen or a hydrocarbyl radical of 1-12 carbon atoms. In particular, the present invention relates to catalyst components suitable for the stereospecific polymerization of olefins, comprising Ti, Mg, halogens and an electron-donating compound selected from specifically substituted maleic acid esters (substituted maleates). Said catalyst components when used in the polymerization of olefins and in particular of propylene, are capable of providing polymers with high yields and with a satisfactory isotactic index expressed in terms of high xylene insolubility.

Unsubstituted maleates and certain substituted maleates are known in the art, and their use as electron donor compounds in the preparation of supported Ziegler-Natta catalyst components has also been disclosed.

EP-A-45977 discloses the use of unsubstituted maleates as internal donors in catalyst components for olefin polymerization. The results obtained are unsatisfactory both in terms of activity and stereospecificity. In USP 5,436,213, esters of maleic or fumaric acids, substituted by a C1-C20 hydrocarbon group, are mentioned generically. The specifically disclosed subject matter is directed only to 2-methyl-substituted-maleates and in particular to 2-diethyl-methylmaleate, disobutyl-2-methylmaleate and 2-didecyl-methylmaleate. Such specific maleates show only minor improvements over unsubstituted maleates. However, as a whole, the performance of the catalysts containing these donors is not satisfactory, in particular in terms of activity. Japanese patent application 58 (1983) -138708 discloses a process for the polymerization of olefins carried out in the presence of a catalyst, one of whose components contains magnesium, titanium, halogen and an electron donor which can also be a ester between a straight chain alcohol and a substituted or unsubstituted maleic acid. The best catalysts according to the subject matter disclosed in said patent would be those containing a C1-C4 alkyl monosubstituted maleic acid ester. However, the polymerization results disclosed in said patent application show that also with the preferred donors, the catalysts have not particularly attractive yields in terms of activity and stereospecificity. Taking into account what is disclosed in the art, it would appear that ZN supported catalyst components containing maleic acid esters as internal donors would not be satisfactory in the polymerization of olefins and in particular of propylene.

Therefore, it has been very surprising to discover that certain specific substituted maleates, when used as internal donors, can give rise to catalyst components that show a balance of characteristics in terms of activity and stereospecificity that makes them particularly suitable for the polymerization of olefins. In fact, said catalysts show much improved activities and / or stereospecificity over the catalyst components that contain the maleates of the prior art as internal donors.

Accordingly, the present invention relates to a solid catalyst component for the polymerization of olefins CH2 = CHR in which R is hydrogen or a hydrocarbon radical with 1-12 carbon atoms, comprising Mg, Ti, halogen and a donor of electrons selected from maleates of formula (I):

OR

R_K Chi-OR 'γ-OR' or wherein R 'is a C1-C20 hydrocarbon group optionally containing heteroatoms, Ri is a C1-C20 hydrocarbon group optionally containing heteroatoms and R2 is H or a C1-C20 hydrocarbon group optionally containing heteroatoms, provided that when R2 is H, Ri is isobutyl or a C5C20 hydrocarbon group.

When R2 is H, Ri is preferably a primary alkyl group having 5 to 10 carbon atoms or a cycloalkyl group. When R₁ and R₂ are other than H, they are preferably selected from C1-C10 alkyl groups.

The R 'groups are preferably primary alkyl, arylalkyl or alkylaryl groups, having 2 to 10 carbon atoms. Most preferably they are branched primary alkyl groups having 2 to 8 carbon atoms. Examples of suitable R 'groups are methyl, ethyl, n-propyl, n-butyl, isobutyl, neopentyl, 2-ethylexy and trifluoropropyl groups.

ES 2 297 014 T3

Specific examples of suitable maleates of formula (I) are: Diethyl 2-isobutylmaleate, Diisobutyl 2-isobutylmaleate, Di-n-butyl 2-isobutylmaleate, Bis (trifluoropropyl) 2-isobutylmaleate, Diethyl 2-n-pentylmaleate, Diisobutyl 2n-pentylmaleate, Diethyl 2-cyclohexylmaleate, Diisobutylmaleate, Diisobutylmaleate, Diisobutyl 2-cyclohexylmaleate -n-Butyl 2-cyclohexylmaleate, Diethyl 2n-decylmaleate, Diisobutyl 2-n-decylmaleate, Diethyl 2-cyclopentylmaleate, Diisobutyl 2-cyclopentylmaleate, Dimethyl 2-cyclopentylmaleate, Diethyl 2-n-decylmaleate, Diethyl 2-cycloheptylmaleylmaleate, Diethyl 2-cycloheptylmaleylmaleate, Diethyl 2-cycloheptylmaleylmaleate Diisobutyl 2-benzylmaleate, Diethyl 2-cyclohexylmethylmaleate, Diethyl 2- (2-ethylhexyl) maleate, Diethyl 2- (1,3-dimethylbutyl) maleate, Diethyl 2- (2pentyl) maleate Diethyl 2-isopentylmaleate, Diethyl 2-neopentylmaleate, Diethyl 2- (3-pentyl) maleate, Diethyl 2- (cyano-ethyl) maleate Diethyl, 2- (3,3,3-trifluoropropyl) maleate, Diethyl 2- (3-amino-propyl) maleate Diethyl 2- (2, 2,2-trifluoro-1-methylethyl) maleate, Diethyl 2,3-dimethylmaleate, Diethyl 2,3-diisobutylmaleate, Diisobutyl 2,3-diisobutylmaleate, Di-n-butyl 2,3-diisobutylmaleate, Bis (trifluoropropyl) 2,3-diisobutylmaleate, Diethyl 2,3-di-n-pentylmaleate, Diisobutyl 2,3-di-n-pentylmaleate, Diethyl 2,3-dicyclohexylmaleate, Diisobutyl 2 , 3-dicyclohexylmaleate, Di-n-butyl 2,3-dicyclohexylmaleate, Diethyl 2,3-di-n-decylmaleate, Diisobutyl 2,3-di-n-decylmaleate, Diethyl 2,3-dicyclopentylmaleate, Diisobutyl 2,3- Dicyclopentylmaleate, Dimethyl 2,3-dicyclopentylmaleate, Diethyl 2,3-dicycloheptylmaleate, Diethyl 2,3-disecbutylmaleate, Diethyl 2,3-dibenzylmaleate, Diisobutyl 2,3-dibenzylmaleate Diethyl 2,3-dicyclohexylmethylmaleate, Diethyl 2,3-bis (2-ethylhexyl) maleate, Diethyl 2,3-bis (1,3-dimethylbutyl) maleate, Diethyl 2,3 -bis (2-pentyl) maleate, Diethyl 2,3-diisopentylmaleate, Diethyl 2,3-dineopentylmaleate, Diethyl 2,3-bis (3-pentyl) maleate, Diethyl 2,3-bis (cyano-ethyl) maleate, Diethyl 2, 3-bis (3,3,3-trifluoropropyl) maleate, Diethyl 2,3-bis (3-amino-propyl) maleate, Diethyl 2,3-bis (2,2,2-trifluoro-1-methylethyl) maleate, Diethyl 2-isobutyl3-methylmaleate, Diisobutyl 2-isobutyl-3-methylmaleate, Di-n-butyl 2-isobutyl-3-methylmaleate, Diethyl 2-n-pentyl-3-ethylmaleate, Diisobutyl 2-n-pentyl-3-n -butylmaleate, Diethyl 2-cyclohexyl-3-propylmaleate, Diisobutyl 2-cyclohexyl-3-isopropylmaleate, Di-n-butyl 2-cyclohexyl-3-secbutylmaleate.

As explained above, the catalyst components of the invention comprise, in addition to the electron donors mentioned, Ti, Mg and halogen. In particular, the catalyst components comprise a titanium compound having at least one Ti-halogen bond and the mentioned electron-donating compound supported on a Mg halide. Magnesium halide is preferably MgCl₂ in active form, which is widely known from patent literature as a support for Ziegler-Natta catalysts. USP 4,298,718 and USP 4,495,338 were the first to describe the use of these compounds in Ziegler-Natta catalysis. It is known from these patents that magnesium dihalides in active form used as support or co-support in catalyst components for olefin polymerization are characterized by an X-ray spectrum in which the most intense diffraction line that appears in the spectrum of the light from the non-active halide decreases in intensity and is replaced by a halo whose maximum intensity is shifted at smaller angles to that of the more intense line.

The preferred titanium compounds used in the catalyst component of the present invention are those that contain at least one Ti-halogen bond. TiCl is preferably used₄, TiCl₃ and Ti-haloalcoholates of formula Ti (OR)_nyX_Y, where n is the valence of titanium, X is a halogen and y is a number between 1 and n.

The preparation of the solid catalyst component can be carried out according to various methods. According to one of these methods, the anhydrous magnesium dichloride and the maleates are ground together under conditions in which the activation of the magnesium dichloride takes place. The product obtained in this way can be treated one or more times with an excess of TiCl₄ at a temperature between 80 and 135 ° C. This treatment is followed by washing with hydrocarbon solvents until the chloride ions disappear. According to another method, the product obtained by co-grinding the magnesium chloride in anhydrous state, the titanium compound and the maleate is treated with halogenated hydrocarbons such as 1,2-dichloroethane, chlorobenzene, dichloromethane, etc. The treatment is carried out for a time interval between 1 and 4 hours and at a temperature between 40 ° C and the boiling point of the halogenated hydrocarbon. The product obtained is generally washed with inert hydrocarbon solvents such as hexane.

According to another method, the magnesium dichloride is pre-activated according to well known methods and then treated with an excess of TiCl₄ at an approximate temperature of 80 to 135 ° C containing in solution a maleate of formula (I). The treatment with TiCl4 is repeated and the solid is washed with hexane in order to remove any TiCl4 that has not reacted.

Another method comprises the reaction between magnesium alcoholates or chloroalcoholates (in particular chloroalcoholates prepared according to US 4,220,554) and an excess of TiCl₄ comprising the maleate of formula (I) in solution at a temperature of approximately 80 to 120 ° C.

According to a preferred method, the solid catalyst component can be prepared by reacting a titanium compound of formula Ti (OR)_nyX_Y, where n is the valence of titanium and y is a number between 1 and n, preferably TiCl₄, with a magnesium chloride derived from an adduct of formula MgCl₂-pROH, in which p is a number between 0.1 and 6, preferably between 2 and 3.5 and R is a hydrocarbon radical having 1-18 carbon atoms. The adduct can be suitably prepared in spherical form by mixing alcohol and magnesium chloride in the presence of an inert hydrocarbon immiscible with the adduct working under stirring conditions at the melting temperature of the adduct (100-130 ° C). The emulsion is then rapidly cooled thereby causing the adduct to solidify in the form of spherical particles. Examples of spherical adducts prepared according to this procedure described in USP 4,399,054 and USP 4,469,648 are described. The adduct obtained in this way can be reacted directly with the Ti compound or it can

ES 2 297 014 T3 be previously subjected to controlled thermal dealcoholation (80-130 ° C) in order to obtain an adduct in which the number of moles of alcohol is generally less than 3, preferably between 0.1 and 2.5 . The reaction with the Ti compound can be carried out by suspending the adduct (in alcohol or in its own state) in TiCl₄ cold (generally 0 ° C), the mixture being heated to 80-130 ° C and kept at this temperature for 0.5-2 hours. Treatment with TiCl₄ it can be carried out one or more times. Maleate can be added during treatment with TiCl₄. Treatment with the electron donor compound can be repeated one or more times.

The preparation of spherical catalyst components is described, for example, in European patent applications EP-A-395083, EP-A-553805, EP-A-553806, EPA-601525 and in WO98 / 44009.

The solid catalyst components obtained according to the method indicated above, show a surface area (by the BET method) generally comprised between 20 and 500 m²/ g and preferably between 50 and 400 m²/ g, and a total porosity (by the BET method) greater than 0.2 cm³/ g, preferably between 0.2 and 0.6 cm³/ g. The porosity (Hg method) due to pores with radii up to 10,000 A is generally between 0.3 and 1.5 cm³/ g, preferably between 0.45 and 1 cm³/ g.

Another method of preparing the solid catalyst component of the invention comprises the halogenation of magnesium dihydrocarbyloxide compounds, such as magnesium dialkoxide or diaryloxide with a solution of TiCl.₄in an aromatic hydrocarbon (such as toluene, xylene, etc.) at temperatures between 80 and 130 ° C. The treatment with TiCl4 in an aromatic hydrocarbon solution can be repeated one or more times and the maleate is added during one or more of these treatments.

In any of these methods of preparation, the desired maleate can be added as such or, alternatively, it can be obtained "in situ" using an appropriate precursor capable of being transformed into the desired electron-donating compound by means, for example, of known chemical reactions such as esterification, trans-spherification, etc. In general, maleate is used in a molar ratio with respect to MgCl₂ 0.01 to 1, preferably 0.05 to 0.5.

The solid catalyst components according to the present invention are converted into olefin polymerization catalysts by reacting them with organoaluminum compounds according to known methods.

In particular, the object of the present invention is a catalyst for the polymerization of olefins CH₂= CHR in which R is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms, the reaction product comprising:

(a) a solid catalyst component as described above;

(b) an alkylaluminum compound and optionally (c) one or more electron donor compounds (external donor).

The Al-alkyl compound (b) is preferably selected from trioalkylaluminum compounds such as, for example, triethylaluminum, triisobutylaluminum, tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum. It is also possible to use mixtures of trialkylaluminums with alkylaluminum halides, alkylaluminum hydrides or alkylaluminum sesquichlorides such as AlEt.₂ Cl and Al₂Et₃Cl₃.

The external donor (c) can be of the same type or it can be different with respect to the maleates of formula (I). Suitable external electron-donating compounds include silicon compounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines, heterocyclic compounds and particularly 2,2,6,6-tetramethyl piperidine, ketones and 1,3-diethers of the general formula (II ):

<img file="ES2297014T3_D0001.tif" />

in which R^I, R¹¹, R^In, R^IV, R^V and R^SAW the same or different from each other, they are hydrogens or hydrocarbon radicals having from 1 to 18 carbon atoms and R^VI1 and R^VI11, the same or different from each other, have the same meaning as R¹ -R^SAW except

ES 2 297 014 T3 which cannot be hydrogen; one or more of the R groups¹ - R^VI11 they can be linked in a loop. 1,3-diethers in which R^VI1 and R^VI11 are selected from the radicals Ci-C₄ I rent.

Another class of preferred external donor compounds is that of the silicon compounds of formula R_to⁵Rb⁶Yes (OR⁷) c, in which a and b are integers that have a value between 0 and 2, c is an integer with a value between 1 and 3 and the sum (a + b + c) is 4; R⁵, R⁶ and R⁷ are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms optionally containing heteroatoms. Silicon compounds in which a is 1, b is 1, c is 2, at least one of R are particularly preferred⁵ and R⁶ are selected from branched alkyl, cycloalkyl or aryl groups with 3-10 carbon atoms optionally containing heteroatoms and R⁷ is a group C₁-C₁₀ alkyl, in particular methyl. Examples of such preferred silicon compounds are methylcyclohexyldimethoxysilane, diisopropyldimethoxysilane, diphenyldimethoxysilane, methyl-t-butyldimethoxysilane, dicyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-t-butyldimethoxysilane and 1,1, 1-dimethylano-pyroxysilane and 1,1,1-tridinyl-pyroxypropyl. Furthermore, silicon compounds in which a is 0, c is 3, R⁶ is a branched alkyl or cycloalkyl group optionally containing heteroatoms and R⁷ is methyl. Examples of such preferred silicon compounds are cyclohexyltrimethoxysilane, t-butyltrimethoxysilane and texyltrimethoxysilane.

The electron donating compound (c) is used in an amount such that it provides a molar ratio between the organoaluminum compound and said electron donating compound (c) of between 0.1 and 500, preferably between 1 and 300 and more preferably between 3 and 100. As indicated above, when used in the (co) polymerization of olefins, and in particular of propylene, the catalysts of the invention make it possible to obtain, with high yields, polymers having a high isotactic index (expressed by high insolubility in xylene XI), thus showing an excellent balance of characteristics. This is particularly surprising in view of the fact that, as can be seen from the comparative examples below, the use of prior art maleates as internal electron donors provides poorer results in terms of yields and / or insolubility in xylene.

Therefore, another objective of the present invention constitutes a process for the (co) polymerization of CH olefins.₂= CHR where R is hydrogen or a hydrocarbyl radical with 1-12 carbon atoms, carried out in the presence of a catalyst as described above.

Said polymerization process can be carried out according to known techniques, for example, emulsion polymerization using an inert hydrocarbon solvent as diluent or bulk polymerization using the liquid monomer (for example, propylene) as the reaction medium. Furthermore, it is possible to carry out the polymerization process in fluidized or mechanically stirred.

The polymerization is generally carried out at a temperature between 20 and 120 ° C, preferably 40 to 80 ° C. When the polymerization is carried out in the gas phase, the operating pressure is generally between 0.5 and 10 MPa, preferably between 1 and 5 MPa. In bulk polymerization, the operating pressure is generally between 1 and 6 MPa, preferably between 1.5 and 4 MPa. Hydrogen or other compounds capable of acting as chain transfer agents can be used to control the molecular weight of the polymer.

The following examples are indicated in order to better illustrate the invention without limiting it.

Characterizations

Maleate preparation

The monosubstituted maleates according to formula (I) used in the present invention can be prepared, for example, by reacting diethyl acetylene dicarboxylate with the corresponding alkyl magnesium chloride in the presence of a copper (I) complex.

As an example, the synthesis of diethyl 2-isobutyl maleate is given below.

A mechanically stirred suspension of copper (I) brumide-dimethylsulfide complex (20.4 g, 99.0 mmol) in 500 mL of THF was cooled to -40 ° C and treated dropwise with a 2.0 M solution of i-butylmagnesium chloride in THF (49.5 mL, 99.0 mmol) under a dry nitrogen atmosphere. After stirring at -40 ° C for 2 hours, the reaction mixture was cooled to -78 ° C and then treated dropwise with a solution of diethyl acetylene dicarboxylate (13.2 mL, 82.5 mmol) in 160 mL of THF. After the addition was complete, the mixture was stirred at -78 ° C for 1 hour, quenched with saturated aqueous NH solution.₄Cl and then slowly warmed to room temperature and stirred at this temperature for another 30 minutes. The organic phase was separated and the water phase was completely extracted with ether. The combined organic extracts were washed with saturated aqueous NH solution.₄Cl, then with salt, dried over Na₂SW₄ and it was vacuum distilled to get 14.8 g (79% yield, boiling point 74-75 ° C / 1 mm Hg) of diethyl 2-i-butylmaleate as a colorless oil.

Propylene polymerization: general process

In a 4-liter autoclave purged with a nitrogen stream at 70 ° C for one hour, 75 ml of anhydrous hexane containing 800 mg of AlEt were introduced into a propylene flow at 30 ° C₃, 79.8 mg of dicyclopentyldimethoxysilane and

ES 2 297 014 T3 mg of solid catalyst component. The autoclave was closed. 1.5 Nl of hydrogen were added and then, with stirring, 1.2 kg of liquid propylene. The temperature rose to 70 ° C in five minutes and the polymerization was carried out at that temperature for two hours. Unreacted propylene was removed, the polymer was recovered and dried at 70 ° C under vacuum for three hours, then weighed and fractionated with o-xylene to determine the amount of the insoluble xylene fraction (XI) at 25 ° C .

Determination of XI

2.5 g of the polymer was dissolved in 250 ml of o-xylene with stirring at 135 ° C for 30 minutes, then the solution was cooled to 25 ° C and after 30 minutes the insoluble polymer was filtered off. The resulting solution was evaporated in a nitrogen stream and the residue was dried and weighed to determine the percentage of soluble polymer and then the fraction of insoluble xylene (%) by difference.

Examples

Examples 1-5 and Comparative Examples 1-3

Preparation of solid catalyst components

250 ml of TiCl were introduced into a 500 ml four-neck flask purged with nitrogen.₄ at 0 ° C. Then 10.0 g of MgCl were added with stirring.₂-2.8C₂H₅Microspheroidal GH (prepared according to the method described in example 2 of USP 4,399,054 but operating at 3,000 rpm instead of 10,000) and an amount of maleate such that it provides, with respect to Mg, a molar ratio of 6. The temperature was raised to 100^toC and held for 120 minutes. The stirring was then discontinued, the solid product was allowed to settle and the supernatant liquid was siphoned off.

250 ml of TiCl were added₄ fresh. The mixture was reacted at 120 ° C for 60 minutes and then the supernatant liquid was siphoned off. The solid was washed six times with anhydrous hexane (6 x 100 ml) at 60 ° C. Finally the solid was dried in vacuo and analyzed. The type and amount of maleate (% by weight) and the amount of Ti (% by weight) contained in the solid catalyst component are indicated in Table 1. The polymerization results are indicated in Table 2.

TABLE 1

<td>Example</td><td colspan="2">Maleate</td><td>You</td>

<td></td><td>Guy</td><td>wt%</td><td>Wt%</td>

<td> 1</td><td>Diethyl 2-isobutylmaleate</td><td> 8</td><td> 3 2 ^¿ 10</td>

<td> 2</td><td>Diethyl 2-n-pentylmaleate</td><td> 10</td><td> 2.8</td>

<td> 3</td><td>Diethyl 2-cyclohexylmaleate</td><td> 8.7</td><td> 3.4</td>

<td> 4</td><td>Diethyl 2-n-decylmaleate</td><td> 6</td><td> 3.7</td>

<td> 5</td><td>Diethyl 2-cyclopentylmaleate</td><td> 7.5</td><td> 3.8</td>

<td>Comp. 1</td><td>Diethyl maleate</td><td> 10.4</td><td> 5.4</td>

<td>Comp. 2</td><td>Diethyl 2-methylmaleate</td><td> 8.7</td><td> 15 2.6</td>

<td>Comp. 3</td><td>Din-butyl maleate</td><td> 9.4</td><td> 3.5</td>

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TABLE 2

<td>Example</td><td>Exercise (Kg / g)</td><td>II (%)</td>

<td> 1</td><td> 45</td><td> 97.2</td>

<td> 2</td><td> 41</td><td> 97.2</td>

<td> 3</td><td> 54</td><td> 97.4</td>

<td> 4</td><td> 43</td><td> 97</td>

<td> 5</td><td> 38</td><td> 96.5</td>

<td>Comp. 1</td><td> 16</td><td> 93.9</td>

<td>Comp. 2</td><td> 26</td><td> 96.6</td>

<td>Comp. 3</td><td> 26</td><td> 96.4</td>