RU2444532C2 - Components of catalyst for polymerisation of olefins and catalysts made from said components - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention describes catalyst components containing Ti, Mg, Cl and an optional OR¹ group, in which R¹ denotes a C1-C20 hydrocarbon group in such an amount that molar ratio OR¹/Ti is less than 0.5, characterised by the following properties: BET specific surface area less than 80 m²/g; total porosity (P_t) measured using a mercury method in the range of 0.70-1.50 cm³/g; the difference (P_t-P_f) is greater than 0.1, where P_T denotes total porosity and P_F denotes porosity due to pores with radius less than or equal to 1 mcm; the amount of Ti in the catalyst component is less than 10 wt %, based on total weight of the catalyst component. Described is a method of producing said components, involving a first step (a) where a compound MgCl₂.m(R^IIIOH)_tH₂O, in which 0.3≤m≤1.7, t ranges from 0.01 to 0.6 and R^III denotes an alkyl, cycloalkyl or aryl radical, having 1-12 carbon atoms, reacts with a titanium compound of formula Ti(OR^II)_nX_y-n, in which n lies between 0 and 0.5, y is titanium valence, X denotes a halogen and R^IV denotes an alkyl radical having 1-8 carbon atoms; and a second step (b) in which a solid product obtained from step (a) undergoes thermal treatment at temperature higher than 100°C. Described also is a method for (co)polymerisation of ethylene in the presence of a catalyst system containing a product of reaction of solid catalyst components described above and an aluminium alkyl compound.

EFFECT: catalyst components exhibit high morphological stability under conditions for low-molecular polymerisation of ethylene, while maintaining high activity.

10 cl, 4 tbl, 16 ex

Description

The present invention relates to catalyst components for the polymerization of olefins CH ₂ = CHR, in which R represents hydrogen or a hydrocarbon radical having 1-12 carbon atoms. In particular, the invention relates to catalyst components suitable for preparing ethylene homopolymers and copolymers, and to catalysts prepared therefrom.

In addition, the invention also relates to ethylene homo- or copolymers having high melt flow and good morphological properties, and to wide molecular weight ethylene polymers with a spherical shape and good morphology.

In particular, the present invention relates to solid catalyst components, including titanium, magnesium and halogen, having a specific combination of physical and chemical characteristics.

In addition, the present invention relates to methods for producing ethylene homopolymers and copolymers characterized by a high melt viscosity ratio expressed on the basis of the F / P ratio, which is the ratio between the melt index measured with a 21.6 kg dosage (melt index F) and index melt measured with a 5 kg dosage (melt index P) determined at 190 ° C according to ASTM D-1238. The indicated F / P ratio is usually considered as a condition for the breadth of the molecular weight distribution (MBP).

MBP is a particularly important characteristic for ethylene (co) polymers, in which it affects both the rheological properties and hence the suitability for melting, and the final mechanical properties. Polyolefins having a broad MBP, especially associated with relatively high average molecular weights, are preferred in blow molding and in a high speed molding process, for example for pipe production. In fact, products characterized by a wide MBP have superior mechanical properties that allow them to be used in applications where high load resistance is required. The processing conditions for these polymers are specific, and in fact, under such conditions, a narrow MBP product cannot be obtained because there will be drawbacks due to melt fracture.

Since it is difficult to have affordable catalysts that offer the correct model of molecular weight distribution and average molecular weight, one of the most common methods for producing broad MBP polymers is a multi-stage method based on obtaining polymer fractions with different molecular weights in each stage, sequentially forming macromolecules with different chain lengths.

The molecular weight control obtained in each stage can be carried out according to various methods, for example, by changing the polymerization conditions or the catalyst system in each stage, or by using a molecular weight regulator. Hydrogen control is the preferred method operating either in suspension or in the gas phase. This latter type of method is currently highly preferred due to the high quality of the products obtained, and due to the low operating costs associated with it.

For a catalyst to be carried out in such a process, the critical step is one in which a low molecular weight fraction is obtained. In fact, one of the important features that the catalyst must possess is the so-called “hydrogen response”, which is the degree of ability to reduce the molecular weight of the polymer obtained relative to the increase in hydrogen concentrations. A higher hydrogen response means that a lower amount of hydrogen is required to produce a polymer with a specific molecular weight. In turn, it would usually also include higher polymerization activity, because the amount of hydrogen, which has a suppressive effect on the activity of the catalyst, may be relatively lower.

In addition, due to the polymerization conditions and the characteristics of the polymer obtained in this stage (in fact, higher brittleness), the catalyst / polymer system is often fragmented into very small particles, which reduce the bulk density of the polymer and create a large number of small particles, which makes it difficult operation of equipment especially in the gas phase of polymerization. One way to solve this problem would be to carry out the step of obtaining the low molecular weight fraction after the first stage in which the high molecular weight fraction is obtained. While this choice can help balance the performance of the equipment, it often implies a deterioration in the final properties of the product, which is less homogeneous. Thus, this would be another important feature of a catalyst having a suitable morphological resistance under conditions of gas-phase polymerization of low molecular weight.

In EP-A-601525, catalysts are disclosed which, in some cases, are capable of producing broad MBP ethylene polymers (reported F / E ratio of 120). Such catalysts obtained by the reaction between the Ti compound and the MgCl ₂ -EtOH adduct, which undergo both physical and chemical desalcoholization, are characterized by a total porosity (mercury method) higher than 0.5 cm ³ / g, surface area (BET method) lower than 70 m ² / g. Pore distribution is also specific; in particular, in all catalysts it is specifically disclosed that at least 50% of the porosity is due to pores with a radius higher than 0.125 μm. The stated patent application reports good applications based on morphological resistance (expressed by bulk density) under standard conditions of suspension polymerization, which, however, do not predict from the nature of the change in properties under conditions of low molecular weight polymerization, when a large amount of molecular weight regulator (hydrogen) is used. The applicant, in fact, carried out polymerization tests under those required conditions and proved that a substantial amount of the catalyst is destroyed in the early stages of polymerization, giving rise to polymer fine fractions and / or with uneven morphology, thus constituting a very low final bulk density.

WO00 / 78820 discloses catalysts capable of producing broad MBP ethylene polymers characterized by total porosity (mercury method), preferably in the range of 0.38-0.9 cm ³ / g, and specific surface area (BET method), preferably in the range of 30-70 m ² / g. Pore distribution is also determined; in particular in all catalysts specifically disclosed, at least 45% of the porosity is due to pores with a radius of up to 0.1 μm. Preferably, the porosity due to pores with a radius of up to 1 μm differs by less than 15% relative to the total porosity. This means that according to the patent application set forth, the contribution of the porosity of the pore fraction with pores greater than 1 μm should preferably be negligible or absent. Also in this case, the catalysts despite the good return under standard polymerization conditions show an unsatisfactory nature of the change in properties under the required test conditions used by the applicant. This is also confirmed in the mentioned document by the fact that when polyethylene with a wide MBP with two consecutive stages of polymerization is obtained, the low molecular weight fraction is always obtained in the second stage of polymerization.

Therefore, there is still a need for a catalyst having high morphological stability under conditions of low molecular weight polymerization of ethylene, while at the same time maintaining high activity characteristics.

Applicant has surprisingly discovered that catalyst components, which are combinations of properties below, are able to satisfy needs. Accordingly, an object of the present invention is a catalyst component comprising Ti, Mg, Cl and optionally OR ¹ groups in which R ¹ represents a C1-C20 hydrocarbon group to an amount such as to obtain an OR ¹ / Ti molar ratio lower than 0.5 characterized by the following properties:

- the specific surface determined by the BET method is lower than 80 m ² / g,

- total porosity (P _T ), measured by the mercury method, in the range of 0.60-1.50 cm ³ / g,

- the difference (P _T -P _F ) is higher than 0.1, in which P _T represents the total porosity and P _F represents the porosity of the pores with a radius equal to or less than 1 μm;

- the amount of Ti in the catalyst component is less than 10% by weight, based on the total weight of the catalyst component.

Preferably, the total porosity (P _T ) ranges from 0.65 and 1.2 cm ³ / g, in particular between 0.70 and 0.90 cm ³ / g. The specific surface area measured by the BET method is preferably lower than 80 and in particular contained between 25 and 70 m ² / g. The porosity measured by the BET method is usually between 0.1 and 0.7, preferably from 0.15 to 0.5 cm ³ / g.

As mentioned above, porosity P _F ; measured by the mercury method and due to pores with a radius equal to or less than 1 μm, is such that the difference (P _T -P _F ) is higher than 0.1, preferably in the range from 0.14 to 0.80 and more preferably , ranging from 0.20 to 0.60.

In a preferred aspect, the catalyst component of the invention comprises a Ti compound having at least one Ti-halogen bond attached to magnesium chloride, which is preferably magnesium dichloride and more preferably magnesium dichloride in active form. In the context of the present application, the term “magnesium chloride” means magnesium compounds having at least one magnesium chloride bond. As mentioned previously, the catalyst component may also contain groups other than halogen, in any case in amounts lower than 0.5 mol for each mole of titanium and preferably lower than 0.3.

In the catalyst component of the invention, the average pore radius for porosity due to pores up to 1 μm is in the range from 600 to 1200 Ǻ.

The particles of the solid component have a substantially spherical morphology and an average diameter between 5 and 150 microns, preferably from 20 to 100 microns and more preferably from 30 to 90 microns. Particles having substantially spherical morphology are those in which the ratio between the major axis and the smaller axis is equal to or lower than 1.5 and preferably lower than 1.3.

Magnesium dichloride in its active form is characterized by X-ray spectra in which the most intense diffraction line that appears in the spectrum of inactive chloride (crystal lattice parameter 2.56 Ǻ) decreases in intensity and expands to such an extent that it becomes completely or partially merged with the line reflection incident on the lattice distance (d) of 2.95 Ǻ. When the merger is completed, a single formed wide peak has a maximum of intensity, which shifts to the corners lower than the corners of the most intense line.

The solid components of the catalyst of the invention may also include an electron-donor compound (internal donor) selected, for example, from ethers, esters, amines and ketones. The specified compound is necessary when the component is used in the stereoregular (co) polymerization of olefins such as propylene, 1-butene, 4-methyl-pentene-l. In particular, the internal electron-donor compound may be selected from alkyl, cycloalkyl and aryl ethers and polycarboxylic acid esters, such as, for example, phthalic and maleic acid esters, in particular n-butyl phthalate, diisobutyl phthalate, di-n-octyl phthalate.

Other electron donor compounds, preferably used, are 1,3-diesters, disclosed, in particular, in EP361494, EP361493, and EP728769.

The electron-donor compound is usually present in a molar ratio relative to magnesium, comprised between 1: 4 and 1:20. In some cases, it may also be present in lower amounts, such as to obtain a molar ratio of magnesium / donor higher than 20.

Preferred titanium compounds have the formula Ti (OR ^II ) _n X _yn in which n is a number between 0 and 0.5 inclusive, y is the valence of titanium, R ^II is an alkyl, cycloalkyl or aryl radical having 1- 8 carbon atoms, and X represents halogen. In particular, R ^II may be ethyl, isopropyl, n-butyl, isobutyl, 2-ethylhexyl, n-octyl and phenyl, (benzyl); X is preferably chlorine.

If y is 4, n preferably varies from 0 to 0.02; if y is 3, n preferably varies from 0 to 0.015.

A method suitable for producing spherical components mentioned above includes a first step (a) in which a compound MgCl ₂ .m (R ^III OH) tH ₂ O, in which 0.3 ≤ m ≤ 1.7, t is from 0.01 to 0.6, and R ^III represents an alkyl, cycloalkyl or aryl radical having 1-12 carbon atoms, reacts with the titanium compound of the formula Ti (OR ^II ) _n X _yn in which n, y, X and R ^II have the same meaning as defined above.

In this case, MgCl ₂ .mR ^III OH is a Mg dihalide precursor. Such compounds can usually be obtained by mixing alcohol and magnesium chloride in the presence of an inert hydrocarbon immiscible with the adduct, acting under stirring conditions at the melting point of the adduct (100-130 ° C). The emulsion is then rapidly suppressed, thereby causing the adduct to solidify in the form of spherical particles. Representative methods for preparing these spherical adducts are reported, for example, in USP 4,469,648, USP 4,399,054, and WO98 / 44009. Another suitable method of spherization is spray cooling, described, for example, in USP 5100849 and 4829034. Adducts having the desired final alcohol content can be obtained directly using the selected amount of alcohol directly during the preparation of the adduct. However, if adducts with increased porosity are to be obtained, it is convenient to first obtain adducts with more than 1.7 mol of alcohol per mole of MgCl ₂ , and then subjecting them to a thermal and / or chemical dealcoholation process. The thermal method of dealcoholization is carried out in a stream of nitrogen at temperatures between 50 and 150 ° C, until the alcohol content is reduced to a value in the range from 0.3 to 1.7. A method of this type is described in EP-395083.

Typically, these dealkolized adducts also exhibit porosity (measured by mercury) due to pores with a radius of up to 0.1 μm in the range of 0.15 to 2.5 cm ³ / g, preferably 0.25 to 1.5 cm ³ / g

In the reaction of step (a), the Ti / Mg molar ratio is stoichiometric or higher; preferably, this ratio is higher than 3. Even more preferably, a large excess of the titanium compound is used. Preferred titanium compounds are titanium tetragalides, in particular TiCl ₄ . The reaction with compound Ti can be carried out by suspending the adduct in cold TiCl ₄ (usually 0 ° C); the mixture is heated to 80-140 ° C and kept at this temperature for 0.5-8, preferably from 0.5 to 3 hours. Excess titanium compounds can be separated at high temperatures by filtration or sedimentation and siphoning.

In step (b) of the method, the solid product returned from step (a) is subjected to a heat treatment carried out at temperatures higher than 100 ° C, preferably higher than 120 ° C, more preferably higher than 130 ° C, especially higher than 150 ° C and most preferably higher than 160 ° C.

Heat treatment can be carried out in several ways. According to one of them, the solid obtained from step (a) is suspended in an inert diluent, like a hydrocarbon, and then subjected to heating, while maintaining the system with stirring.

According to an alternative technique, a solid can be heated in a dry state by placing it in a device having heated walls sheathed on the outside. While agitation can be achieved by mechanical agitators placed in said device, it is preferable to induce agitation using rotary devices.

According to yet another embodiment, a solid obtained from (a) can be heated by subjecting it to a stream of hot inert gas such as nitrogen, preferably maintaining the solid under fluidized bed conditions.

The heating time is not set, but may vary depending on other conditions, such as the maximum temperature reached. It usually ranges from 0.1 to 10 hours, more specifically from 0.5 to 6 hours. Typically, higher temperatures allow the heating time to be shortened, while, in contrast, lower temperatures may require a longer reaction time. It is also possible to carry out the heating step (b) in the presence of additional compounds, such as, for example, SiCl ₄ , which can also form the liquid medium of the reaction step (b).

According to a further preferred embodiment, the heating step (b) is carried out in the presence of an organometallic aluminum halide. Preferably, it is selected from organoaluminum compounds of the formula R ^VII _z AlX _3-z , in which R ^VII represents a C ₁ -C ₂₀ hydrocarbon group, z represents from 0 to less than 3, preferably from 1 to 2, and X represents halogen, preferably chlorine, iodine or bromine. Preferred organoaluminum compounds are ethylaluminum dichloride (EADC), ethylaluminum dibromide, ethylaluminum diiodide, diethylaluminum chloride (DEAC), diethylaluminum bromide, diethylaluminum iodide and alkyl aluminum sesquichloride (Al ₂ Et ₃ Cl ₃ EAPH), isobutylaluminum dichloride (IBADH) diisobutylaluminum chloride ( DIBAC), isobutylaluminum sesquichloride (IBAP), n-octylaluminum sesquichloride (NOAPH). Mixtures of the aforementioned organoaluminum halides may also be used.

The general conditions under which the heat treatment is carried out can be maintained substantially unchanged even in the presence of organoaluminum halides. However, it was noted that the use of these compounds can reduce the time and / or temperature of the heat treatment. In particular, when said aluminum alkyl halide is present, heat treatment can be carried out with excellent results at temperatures in the range of 120 ° C. to 170 ° C. for a period of time ranging from 0.5 to 6 hours.

Preferably, said organoaluminum halide can be used in a molar ratio relative to the content of Ti atoms present in the solid obtained from (a) in the range from 0.01 to 50, preferably from 0.05 to 20, and more preferably from 0.1 to 1 .

This constitutes a preferred embodiment of the present invention, producing the catalyst component disclosed above by carrying out after step (a) and (b) the further step (c) in which the product obtained from (b) is contacted with an electron-donor compound, preferably selected among ethers, ketones, esters and silicon compounds. Preferably, said electron-donor compound is selected among diesters and diketones, and more preferably among 1,3-diesters.

Preferred diesters are 9.9-dimethoxyfluorene and 1,3-diesters mentioned in EP 728769, among which 9.9-bis (methoxymethyl) fluorene is preferred. Among diketones, aliphatic diketones are preferred, and among them, acetylacetone is most preferred. Contacting is preferably carried out in an inert hydrocarbon as a diluent at a temperature ranging from room temperature to the boiling point of the donor, usually from 40 to 150 ° C and preferably from 50 ° C to 140 ° C. The electron donor compound can be used in a molar ratio with the Ti compound in the solid catalyst component obtained from step (b) in the range from 5 to 0.01, preferably from 1 to 0.1, and more preferably from 0.8 to 0.1. The donor becomes attached to the catalyst component in variable amounts, which, apparently, do not correlate with the effect on morphological stability, that is, with the ability of the catalyst to produce high volume density polymers even when the test conditions used by the applicant are required. In fact, a positive effect on morphological stability is always present, even when the amount of fixed donor is very low or possibly absent. In particular, donor treatment allows the catalyst to have even greater morphological stability, as evidenced by the fact that a polymer with a high bulk density is also available by ethylene polymerization in the presence of a large amount of hydrogen and when triethylaluminum is used as a cocatalyst, which is known as requiring special conditions.

The catalyst components of the invention form catalysts for the polymerization of alpha-olefins CH ₂ = CHR ^VIII , in which R ^VIII is hydrogen or a hydrocarbon radical having 1-12 carbon atoms by reaction with Al-alkyl compounds. In particular, Al-trialkyl compounds, for example Al-trimethyl, Al-triethyl, Al-tri-n-butyl, Al-triisobutyl, are preferred. The Al / Ti ratio is higher than 1 and usually is between 5 and 800.

In the case of stereospecific polymerization of α-olefins, such as, for example, propylene and 1-butene, an electron-donor compound (external donor), which may be the same or different from the compound used as an internal donor, is also commonly used in the preparation of catalyst.

When the internal donor is a polycarboxylic acid ester, in particular phthalate, the external donor is preferably selected from silane compounds containing at least a Si — OR bond having the formula R ^IX _4-n Si (OR ^x ) _n , in which R ^IX is an alkyl, cycloalkyl, aryl radical having 1-18 carbon atoms, R ^X is an alkyl radical having 1-4 carbon atoms, and n is a number between 1 and 3. Examples of these silanes are methyl cyclohexyl-dimethoxysilane , diphenyl-dimethoxysilane, methyl tert-butyl dimethoxysilane, dicyclopentyldimethoxysilane.

It may be preferable to also use 1,3-diesters having the previously described formula. In the case in which the internal donor is one of these diesters, the use of an external donor can be avoided since the stereospecificity of the catalyst is already high enough.

The spherical components of the invention and the catalysts obtained on the basis of this find application in methods for producing several types of olefin polymers.

As mentioned above, the catalysts of the invention are provided with particularly high morphological stability at a high hydrogen concentration to produce a low molecular weight (co) ethylene polymer. The morphological stability of the catalyst of the invention may also be related to their mechanical resistance. In fact, the catalysts of the invention show good resistance when subjected to impact tests. In particular, their resistance was checked by exposing the solid components of the catalyst to flow at a high speed (55 m / s) and a metal plate. Under these conditions, a certain amount of catalyst particles breaks down and becomes fragmented in a smaller particle, thereby lowering the average particle size of the catalyst before testing and thus increasing the weight of fractions having sizes lower than the sizes of the original average size. In the catalyst of the invention, this phenomenon was greatly reduced with a very small amount of finely divided particles obtained and with a limited decrease in the average particle size after the test. Consequently, it has been observed that the catalysts of the invention are particularly suitable for use in a cascade or sequential polymerization processes for the production of broad molecular weight ethylene polymers both in suspension and in the gas phase. Typically, the catalyst can be used to produce: high density ethylene polymers (HDPE, having a density higher than 0.940 g / cm ³ ), including ethylene homopolymers and copolymers of ethylene with alpha-olefins having 3-12 carbon atoms; linear low density polyethylene (LLDPE having a density lower than 0.940 g / cm ³ ) and very low density and ultra low density (LLDPE and LLDPE having a density lower than 0.920 g / cm ³ to 0.880 g / cm ³ cm ³ ), consisting of copolymers of ethylene with one or more alpha olefins having from 3 to 12 carbon atoms, having a molar content of units derived from ethylene, higher than 80%; elastomeric copolymers of ethylene and propylene and elastomeric triple copolymers of ethylene and propylene with small proportions of diene having a weight content of units derived from ethylene containing between about 30 and 70%, isotactic polypropylenes and crystalline copolymers of propylene and ethylene and / or other alpha olefins having a content of units derived from propylene higher than 85% by weight; high impact polymers of propylene obtained by sequential polymerization of propylene and mixtures of propylene with ethylene containing up to 30% by weight of ethylene; copolymers of propylene and 1-butene having a number of units derived from 1-butene containing between 10 and 40% by weight.

However, as previously indicated, they are particularly suitable for the preparation of polymers with a broad MBP and, in particular, homopolymers and copolymers of ethylene with a broad MBP containing up to 20 mol.% Higher than α-olefins such as propylene, 1-butene, 1-hexene , 1-octene.

One additional advantage of the catalyst described in this application is that it can be used essentially in the polymerization process, by introducing it directly into the reactor without the need for prepolymerization. This allows you to simplify the industrial installation and simplify the method of producing the catalyst.

The main method of polymerization in the presence of catalysts obtained from the catalytic components of the invention can be carried out according to known methods either in the liquid or gas phase, using, for example, the known fluidized bed technique, or under conditions in which the polymer is mechanically mixed. However, the preferred method is carried out in the gas phase in a fluidized bed reactor. Whatever method is included, the catalyst described above, due to their good morphological stability of the particles, can withstand polymerization temperatures higher than standard temperatures that are higher than 80 ° C and in particular in the range of 85-100 ° C. Since higher polymerization temperatures make it possible to simultaneously obtain higher yields and a more effective reduction in high temperature due to the greater difference between the polymerization temperature and the coolant, this leads to a very increased productivity of the catalyst of the invention.

Examples of gas phase methods in which it is possible to use the spherical components of the invention are described in WO92 / 21706, USP 5733987 and WO93 / 03078. In these methods, a preliminary contacting step of the catalyst components, a prepolymerization step, and a gas phase polymerization step in one or more reactors in a series of fluidized or mechanically mixed beds are included, even if, as mentioned above, they are not strictly required with the catalyst of the invention.

Therefore, in the case in which the polymerization takes place in the gas phase, the method of the invention is preferably carried out according to the following steps:

(a) contacting the catalyst components in the absence of a polymerizable olefin or optionally in the presence of said olefin in amounts of not more than 20 g per gram of solid component (A);

(b) gas phase polymerization of ethylene or its mixture with α-olefins CH ₂ = CHR, in which R is a hydrocarbon radical having 1-10 carbon atoms in one or more fluidized or mechanically stirred bed of reactors using a catalyst system obtained from (a).

As mentioned above, to further increase the MWR of the product, the method of the invention can be carried out in two or more reactors operating under different conditions and optionally reusing at least partially the polymer that is formed in the second reactor in the first reactor. Typically, two or more reactors operate with different concentrations of a molecular weight regulator, or at different polymerization temperatures, or both. Preferably, the polymerization is carried out in two or more stages, working with different concentrations of the molecular weight regulator.

As already explained, one of the most interesting features of the above described catalysts is the ability to produce ethylene polymers with a low molecular weight, expressed using a high melt index “E”, and good morphological properties, expressed using high bulk density values. In particular, said ethylene polymers have a melting index E higher than 50 and bulk densities higher than 0.35. Most preferred are polymers that have an EI greater than 70 and bulk density higher than 0.37, and most preferred are polymers with an E E in the range of 80-400 and bulk density in the range of 0.4-0, 6. When such polymers are obtained in the low molecular weight polymerization stage of a multistage process, they allow ethylene polymers having at the same time a broad MBP, usually expressed by a melt viscosity ratio (F / P) of more than 20, preferably more than 25 and more preferably more than 35, which is the ratio between the melting index measured with a 21.6 kg dosage (melting index F) and the melting index measured with a 5 kg dosage (melting index P) determined at 190 ° C according to ASTM D-123 8, a bulk density of more than 0.44, preferably more than 0.46, and preferably good homogeneity, expressed by a variety of gels (as defined below), having a diameter greater than 0.2 mm, lower than 70, and preferably lower than 60. In addition, preferably, the films do not contain any gels with a diameter higher than 0.5 mm. Once used in the production of films or pipes, in fact, the polymers showed very good processing ability, while the extruded products showed a very low number of gels. The polymer is obtained in the form of spherical particles, meaning that the ratio between the major axis and the smaller axis is equal to, or lower than 1.5, and preferably lower than 1.3.

The following examples are given to further describe and not limit the present invention.

Properties are defined according to the following methods:

- Porosity and specific surface with nitrogen: determined according to method B.E.T. (used apparatus SORPTOMATIC 1900 by Carlo Erba).

- Porosity and specific surface with mercury:

Measurements are made using the "Porosimeter 2000 series" by Carlo Erba.

Porosity is determined by the absorption of mercury under pressure. For this definition used create a calibrated dilatometer (diameter 3 mm) CD ₃ (Carlo Erba), associated with a vessel with mercury and a high vacuum pump (1 · 10 ^-2 mbar). A weighted amount of sample is placed in the dilatometer. The apparatus is then placed under high vacuum (<0.1 mm Hg) and maintained under these conditions for 20 minutes. The dilatometer is then connected to the mercury vessel and the mercury is allowed to flow slowly into it until it reaches the level noted on the dilatometer at a height of 10 cm. The valve that connects the dilatometer to the vacuum pump is closed, and then the mercury pressure is gradually increased with nitrogen to 140 kg / cm ² . Under pressure, mercury enters the pores, and the level decreases according to the porosity of the material.

Porosity (cm ³ / g), both total and porosity due to pores up to 1 μm, the pore distribution curve and average pore size are directly calculated from the integral pore distribution curve, which is a function of reducing the volume of mercury and the applied pressure and appear to be a porosimeter connected to a computer that is equipped with the MILESTONE 200 / 2.04 C.Erba program.

- MIE yield index: ASTM-D 1238 condition E

- MIF yield index: ASTM-D 1238 condition F

- MIP yield index: ASTM-D 1238 condition P

Bulk Density: DIN-53194

Effective Density: ASTM-D 792

Ti Definition ^(Red)

0.5 g of the sample in powder form was dissolved in 100 ml of 2.7 M HCl in the presence of solid CO ₂ . The solution thus obtained is then subjected to volumetric titration with a solution of FeNH ₄ (SO ₄ ) ₂ 12H ₂ O 0.1N, in the presence of solid CO ₂ , using the NH ₄ SCN equivalence point (25% aqueous solution) as an indicator. Stoichiometric calculations based on the amount of titration agent consumed give the weight amount of Ti ³⁺ in the sample.

Determination of Mg, Ti ( _total ) and Al: was performed using inductively coupled plasma emission spectroscopy (ICP) on an ICP SPECTROMETER ARL Accuris.

The sample was obtained by analytically weighing, in a “fluxy” platinum crucible, 0.1–0.3 g of catalyst and 3 g of lithium metaborate / tetraborate 1/1 mixture. The crucible is placed in a weak Bunsen burner flame during the combustion stage, and then after adding a few drops of KI solution, the solution is placed in a special Claisse Fluxy apparatus for complete combustion. The precipitate was collected with a solution of 5% v / v. HNO ₃ and then analyzed using ICP at the following wavelengths: Magnesium, 279.08 nm; Titanium, 368.52 nm; Aluminum, 394.40 nm.

Determination of Cl: carried out using potentiometric titration.

Determination of OR groups: by gas chromatographic analysis.

Gel number determination: 45 kg of polymer is activated with Irgafox 168 (0.15 wt.%), ZnO (0.15 wt.%), Zinc stearate (0.05 wt.%), PPA-VITOW Z100 (0.03 wt. %) and granulated using a WP (Werner & Pfliderer) ZSK 40 twin-screw extruder plus a gear pump plus an aqueous tabletting machine, keeping the temperature at 230 ° C in all sections at 38 kg / h at the outlet. The product is then extruded into an extrusion film using a Dolci KRC 40 grooved feed-based extruder with a drum temperature profile of 220-225-225-220 ° C and 230-230 ° C in the dead zones. The product yield is 28 kg / h at 50 rpm. The film is extruded with a blow-up coefficient (BUR) of 4: 1 and a neck length of 7.5: 1 at 20 microns of thickness. The determination of the number of gels in m ^{2 is} carried out by visually detecting the number of gels having the size of the longest axis higher than 0.2 mm per part of the extruded film (25 × 7.5 cm size), which was designed by the projector, on an enlarged scale poster. The calculation was made on 5 different parts of the same film, and the final number is given from the expression No = A / S, where No represents the number of gels in m ² , A represents the number of gels calculated on 5 parts of the film, and S represents total surface area in m ^{2 of} these 5 investigated parts of the film.

General Ethylene Polymerization Procedure (Procedure A)

A 4.5-liter stainless steel autoclave equipped with a magnetic stirrer, temperature and pressure indicator, and a supply line for hexane, ethylene and hydrogen was used and cleaned with pure nitrogen at 70 ° C for 60 minutes. Then a solution of 1550 cm ^{3 of} hexane containing 7.7 cm ^{3 of} 10% w / v. TiBAL / hexane was introduced at a temperature of 30 ° C under a stream of nitrogen. Into a separate 200 cm ³ round-bottom glass flask was sequentially introduced 50 cm ³ anhydrous hexane, 1 cm ³ 10% wt./about. a solution of TiBAL / hexane and 0.040 ÷ 0.070 g of the solid catalyst of table 1. They were mixed together for 10 minutes at room temperature and introduced under a stream of nitrogen into the reactor. The autoclave was closed, then the temperature was raised to 85 ° C, hydrogen (9 bar partial pressure) and ethylene (3.0 bar partial pressure) were added.

With continuous stirring, the total pressure was maintained at 85 ° C for 120 minutes by feeding ethylene. At the final stage, the reactor was depressurized, and the temperature dropped to 30 ° C. The recovered polymer was dried at 70 ° C under a stream of nitrogen and analyzed.

General Ethylene Polymerization Procedure (Procedure B)

The procedure was carried out under the same conditions disclosed for method (A), with the only difference being that triethyl aluminum was used instead of triisobutyl aluminum.

EXAMPLES

Obtaining a spherical base (Adduct MgCl ₂ / EtOH)

Magnesium chloride and alcohol adduct were prepared by the following method described in Example 2 of USP 4399054, but operating at 2000 rpm instead of 10000 rpm.

The adduct containing about 3 moles of alcohol had an average size of about 70 microns with a dispersion range of about 45-100 microns.

Example 1

a) Obtaining the intermediate solid component

Magnesium chloride and an alcohol adduct containing about 3 moles of alcohol were obtained by the following method described in Example 2 of USP 4,995,054, but operating at 2,000 rpm instead of 10,000 rpm. The adduct was subjected to heat treatment under a stream of nitrogen at a temperature range of 50-150 ° C until a 25% alcohol by weight was reached.

In a 2 L four-necked round flask purified with nitrogen, 1 L of TiCl ₄ was introduced at 0 ° C. Then, at the same temperature, 70 g of a spherical adduct MgCl ₂ / EtOH containing 25 wt.% Ethanol and prepared as described above was added with stirring. The temperature was raised to 140 ° C after 2 hours and maintained for 60 minutes. Then the stirring was stopped, the solid product was sedimented and the settled liquid was pumped out. The solid precipitate was then washed once with heptane at 80 ° C and five times with hexane at 25 ° C, dried under vacuum at 30 ° C, and analyzed.

b) heat treatment

In a 250 cm ³ four-necked round flask, purified with nitrogen, 100 cm ³ Isopar-L and 20.9 g of the intermediate of solid component a) previously obtained, were introduced at 25 ° C. With stirring, the temperature was raised to 170 ° C after 45 minutes and maintained for 1 hour. Then the temperature was reduced to 80 ° C, stirring was stopped, the solid product was sedimented for 30 minutes, and the settled liquid was pumped out.

The solid was washed with 100 cm ^{3 of} anhydrous heptane and three times at 25 ° C. Finally, the solid was dried under vacuum and analyzed. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 2

In a 350 cm ³ four-necked round flask, purified with nitrogen, 280 cm ³ Isopar-L and 19.8 g of the intermediate of the solid component a) of example 1 were introduced at 25 ° C. With stirring, the temperature was raised to 180 ° C after 60 minutes and maintained for 3 hours. Then the temperature was reduced to 80 ° C, stirring was stopped, the solid product was sedimented for 30 minutes, and the settled liquid was pumped out. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 3

In a 250 cm ³ four-necked round flask purified with nitrogen, 150 cm ³ Isopar-L and 4 cm ³ 20% w / v. EAHC / hexane solution (6.4 mg Al atoms) was introduced at 25 ° C. The solution was stirred for 10 minutes, then at the same temperature, 15 g of the intermediate of the solid component a) of Example 1, previously prepared, was added with stirring. The temperature was raised to 160 ° C after 40 minutes and maintained for 1 hour. Then the temperature was reduced to 80 ° C, stirring was stopped, the solid product was sedimented for 30 minutes, and the settled liquid was pumped out. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 4

In a 250 cm ³ four-necked round flask purified with nitrogen, 75 cm ³ Isopar-L and 3.2 cm ³ 20% w / v. a solution of EDC / hexane (5.04 mg of Al atoms) was introduced at 25 ° C. The solution was stirred for 10 minutes, then at the same temperature, 15 g of the solid intermediate as component a) of Example 1, previously prepared, was added with stirring. The temperature was raised to 120 ° C after 40 minutes and maintained for 5 hours. Then the temperature was reduced to 80 ° C, stirring was stopped, the solid product was sedimented for 30 minutes, and the settled liquid was pumped out. The solid was washed three times with anhydrous hexane (100 cm ³ ) at 25 ° C, and finally, the solid was dried under vacuum and analyzed. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 5

In a 250 cm ³ four-necked round flask purified with nitrogen, 150 cm ³ Isopar-L and 4 cm ³ 20% w / v. EAHC / hexane solution (6.4 mg Al atoms) was introduced at 25 ° C. The solution was stirred for 10 minutes, then at the same temperature, 15.2 g of a solid intermediate as component a) of Example 1, previously prepared, was added with stirring. The temperature was raised to 180 ° C after 60 minutes and maintained for 3 hours. Then the temperature was reduced to 80 ° C, stirring was stopped, the solid product was sedimented for 30 minutes, and the settled liquid was pumped out. The solid was washed three times with anhydrous hexane (100 cm ³ ) at 25 ° C, and finally the solid was dried under vacuum and analyzed. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 6

In a 250 cm ³ four-necked round flask purified with nitrogen, 150 cm ³ Isopar-L and 2.5 cm ³ 25.5% w / v. a solution of EADC / hexane (5.0 mg of Al atoms) was introduced at 25 ° C. The solution was stirred for 10 minutes, then at the same temperature, 15.1 g of a solid intermediate as component a) of Example 1, previously prepared, was added with stirring. The temperature was raised to 160 ° C after 60 minutes and maintained for 1 hour. Then the temperature was reduced to 80 ° C, stirring was stopped, the solid product was sedimented for 30 minutes, and the settled liquid was pumped out. The solid was washed three times with anhydrous hexane (100 cm ³ ) at 25 ° C, and finally the solid was dried under vacuum and analyzed. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 7

A catalyst component was prepared as described in Example 6 with the only difference that the treatment was carried out at 130 ° C. for 5 hours.

The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 8

A catalyst component was prepared as described in Example 7, with the only difference being that ethyl aluminum diiodide was used instead of EDC and that the treatment was carried out at 130 ° C. for 5 hours. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 9

A catalyst component was prepared as described in Example 7, with the difference that diethylaluminium iodide was used instead of EADC in a molar ratio of Ti 0.5 and that the treatment was carried out at 130 ° C for 5 hours. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 10

A catalyst component was prepared as described in Example 7, with the only difference being that ethyl aluminum dibromide was used instead of EDC and that the treatment was carried out at 130 ° C for 5 hours. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 11

A catalyst component was prepared as described in Example 7, with the difference that diethyl aluminum bromide was used instead of EADC in a molar ratio of Ti 0.5 and that the treatment was carried out at 130 ° C for 5 hours. The analytical results are reported in Table 1, while the obtained polymerization results, using them in the ethylene polymerization procedure A described above, are reported in Table 2.

Example 12

In a 500 ml four-necked round flask equipped with a mechanical stirrer and purified with nitrogen, 200 ml of anhydrous heptane and 2 g of the solid catalyst component obtained as described in Example 7 were charged at room temperature. At the same temperature, an amount of 9.9-dimethoxyfluorene was added dropwise with stirring to achieve an ED / Ti molar ratio of 0.25. The temperature was raised to 50 ° C and the mixture was stirred for 3 hours. Then the stirring was stopped, the solid product was sedimented and the settled liquid was pumped out.

The solid was washed 3 times with anhydrous hexane (3 × 100 ml) at 25 ° C, restored, dried under vacuum and analyzed. The final donor content was 0.8%. The polymerization results obtained using them in the ethylene polymerization procedures A and B described above are reported in Table 2.

Example 13

A catalyst component was prepared as described in Example 12, with the difference that acetylacetone was used instead of 9,9-dimethoxyfluorene. The final donor content was 0.6%. The polymerization results obtained using them in the ethylene polymerization procedures A and B described above are reported in Table 2.

Example 14

A catalyst component was prepared as described in Example 12, with the difference that 9.9-bis (methoxymethyl) fluorene was used instead of 9.9-dimethoxyfluorene and the ED / Ti molar ratio was 0.3. The final donor content was 1.2%. The polymerization results obtained using them in the ethylene polymerization procedures A and B described above are reported in Table 2.

Example 15

A catalyst component was prepared as described in Example 14, with the difference that the treatment temperature was 100 ° C. The final donor content was 1.6%. The polymerization results obtained using them in Method B of ethylene polymerization described above are reported in Table 2.

Comparative Example 1

The solid catalyst component obtained as described in Example 1a was used in Methods A and B of ethylene polymerization described above, and the results are reported in Table 2.

Example 16

Obtaining with wide MBP PE in a cascade polymerization process

The polymerization method was carried out in a facility operating in continuous mode and mainly equipped with a small reactor (precontacting reactor), in which the components of the catalyst are mixed to form a catalyst system, the second reactor receiving the catalyst system formed in the previous step, also equipped with mixing means and two fluidized bed reactors (polymerization reactors) which are under conditions of fluidization with propane.

The following reagents are fed to the precontacting reactor:

- a solid catalyst component obtained as described in example 4, but operating at 130 ° C instead of 120 ° C;

- liquid propane as a diluent;

- a solution of an aluminum alkyl compound.

The temperature is in the range of 10-60 ° C, and the total residence time (first and second reactor) ranges from 15 to 2 hours. Thus, the resulting catalyst system was then fed to a first gas phase fluidized bed reactor operating under the conditions described in Table 3. The polymer obtained in the first gas phase reactor was then transferred to a second gas phase reactor operating under the conditions described in Table 3. Polymer , loaded from the final reactor, was first transferred to a stripping column and then dried at 70 ° C under a stream of nitrogen and weighed. The polymer properties are reported in table 4.

Table 1 Example (BET) Surface Porosity (Hg method) Mg Ti Al EtOH Surface the weight.% the weight.% the weight.% the weight.% m ² / g cm ³ / g cm ³ / g one 19,4 6.5 - 0.1 53.8 0.965 0.672 2 19.3 6.3 - 0.1 51.6 1.012 0.650 3 18.0 5.7 0.1 0.1 25.9 1,142 0.584 four 18,4 5.9 1,0 0.8 30,4 0.924 0.584 5 19.2 6.3 1,2 <0.1 32,5 0.985 0.610 6 19,4 5.9 0.9 0.1 37.0 0,800 0.641 7 17.6 7.5 1,1 0.7 66.6 0.754 0.591 8 16.9 7.3 1,0 0.2 51,4 0.693 0.536 9 16.8 7.5 2.0 0.3 51.6 0.774 0.531 10 17.0 7.2 1,2 0.3 56.5 0.771 0.627 eleven 17.1 7.0 1.9 0.7 48,2 0.786 0.621 Connection one 19.0 6.4 - 1.4 58.7 0.703 0.643

table 2 Example The technique of sex. Exit MI E Critical
pressure (BDP) Morphology BUT Kg PE / g Cat dg / min g / cm ³ one BUT 3.4 93 0.378 spherical 2 BUT 3.2 58 0.396 spherical 3 BUT 3.9 93 0.395 spherical four BUT 4.6 150 0.360 spherical 5 BUT 3.2 one hundred 0.398 spherical 6 BUT 4.2 92 0.406 spherical 7 BUT 4.8 96.2 0.385 spherical 8 BUT 3.4 93.6 0.403 spherical 9 BUT 4.6 110 0.393 spherical 10 BUT 4.1 92 0.400 spherical eleven BUT 5.9 98 0.385 spherical 12 BUT
AT four
4.4 78,2
133 0.435
0,300 spherical
spherical / stratified 13 BUT
AT 3,5
4.6 69
79 0.425
0,303 spherical
spherical / stratified fourteen BUT
AT 4.1
5.2 80
136 0.421
0.330 spherical
spherical / stratified fifteen AT 4.0 200 0.360 spherical Connection one BUT 13.6 113 0.269 stratified

Table 3 Preliminary contact 1- Reactor 2- Reactor Cat. (g / h) AlR _{3
TYPE OF} AlR ₃ / Cat. (g / g) Average time spent (min) T
(° C) Average time spent (min) T °
(° C) 10 Tiba four 13 fifty 60 fifty Table 3 continued The first fluidized bed reactor C ₂
(mol%) H ₂ / C ₂
(mol) Average time spent (h) P
bar hut pressure T
(° C) Yield (kg / h) 9.7 4.06 2.0 24 75 60 Table 3 continued Second fluidized bed reactor Average time spent (h) T
(° C) P
bar hut pressure C ₂ / H ₄
(mol%) H ₂ / C ₂
(mol) C6- / C2 + C6-
(mol) Yield (kg / h) 2.2 75 24 5.2 0.056 0,071 116

Table 4 Final polymer MIP (g / 10 ′) 0.27 MIF / MIP 29.3 Bulk density (kg / dm ³ ) 0.472 The number of gels / m ² > 0.2 mm 40 0.5 ÷ 0.7 mm 0 0.7 ÷ 1.5 mm 0 > 0.5 mm 0

Claims (10)

1. Catalyst components for the polymerization of olefins, including Ti, Mg, Cl and optionally OR ¹ groups in which R ¹ is a C1-C20 hydrocarbon group, to such an amount as to obtain an OR ¹ / Ti molar ratio lower than 0.5, characterized by the following properties:
the specific surface determined by the BET method, lower than 80 m ² / g, the total porosity (P _T ), measured by the mercury method, in the range of 0.70-1.50 cm ³ / g;
the difference (P _T -P _F ) is higher than 0.1, in which P _T represents the total porosity and P _F represents porosity due to pores with a radius equal to or less than 1 μm;
the amount of Ti in the catalyst component is less than 10 wt.%, based on the total weight of the catalyst component. 2. The catalyst components according to claim 1, in which the solid component difference (P _T -P _F ) is in the range from 0.20-0.80. 3. The catalyst components according to claim 1, in which the solid component comprises a Ti compound having at least one Ti-halogen bond attached to magnesium chloride. 4. The method of producing catalyst components according to claim 1, comprising the first stage (a), in which the compound MgCl ₂ · m (R ^III OH) _t H ₂ O, in which 0,3≤m≤1,7, t represents from 0.01 to 0.6 and R ^III represents an alkyl, cycloalkyl or aryl radical having 1-12 carbon atoms, reacts with a titanium compound of the formula Ti (OR ^II ) _n X _yn , in which n is between 0 and 0, 5, y represents the valency of titanium, X represents halogen and R ^IV represents an alkyl radical having 1-8 carbon atoms; and the second stage (b), in which the solid product obtained from stage (a) is subjected to heat treatment carried out at a temperature higher than 100 ° C. 5. The method according to claim 4, in which the heat treatment is carried out at temperatures higher than 120 ° C. 6. The method according to claim 5, in which the heat treatment is carried out in the presence of an organometallic aluminum halide. 7. The method according to claim 6, further comprising a step (c), in which the product obtained from (b) is contacted with an electron-donor compound. 8. The method for the (co) polymerization of ethylene, carried out in the presence of a catalyst system comprising the reaction product of solid catalyst components according to any one of claims 1 to 3 and an aluminum alkyl compound. 9. The method according to claim 8, characterized by the fact that it is carried out in the gas phase. 10. The method according to claim 9, carried out in two or more reactors operating at different concentrations of the molecular weight regulator.