Suspension polymerisation method. RU patent 2476447.

FIELD: chemistry.

SUBSTANCE: invention relates to a method of producing multimodal polyethylene. The method is carried out in at least two reactors connected in series in the presence of an olefin polymerisation catalyst, where 20-80 wt % of a high-molecular weight polymer is obtained in a suspension in the first reactor and 20-80 wt % of a low-molecular weight polymer is obtained in a suspension in the second reactor in the presence of the high-molecular weight polymer. Concentration of solid particles in the second reactor of the low-molecular weight product, which is defined as weight of the polymer divided by total weight of the suspension is at least 35 wt %, more preferably lies in the range of 45-60 wt %, and/or the ratio of the concentration of solid particles in the first reactor to that ratio in the second reactor is maintained at a level below 1.0, preferably in the range of 0.6-0.8. Volume of the second reactor is at least 10%, preferably at least 30%, and even more preferably at least 50%, greater than the volume of the first reactor. The ratio of the average effective concentration of substance in the reactor the low-molecular weight product to the average effective concentration of substance in the reactor of the high-molecular weight product is 0.25-1.5, where the average effective concentration of substance in each reactor is defined as output of polyethylene obtained in the reactor (kg PE/h)/[concentration of ethylene in the reactor (mol %) x residence time in the reactor (h) x rate of feeding catalyst into the reactor (g/h)]. Residence time is defined as the mass of the polymer in the reactor (kg)/rate of removal of the polymer from the reactor (kg/h). The ratio of concentration of ethylene in the liquid phase (mol %) in the second reactor to that ratio in the first reactor is 5 or less, concentration of ethylene in the second reactor is less than 8 mol % and average volume output (defined as polymer output in kg/h per unit volume of the reactor) in all combined reactors is greater than 100 kg/m³/h.

EFFECT: method of producing multimodal polyethylene in two reactors with optimum ratio of dimensions.

13 cl, 1 tbl, 1 ex

The present invention relates to the polymerization of olefins in the reactors of the liquid phase, and more specifically to the polymerization in two or more reactors in sequence.

Polymerization of olefins in the liquid phase is well-known, it monomer and optional polymerize in the presence of a catalyst in diluent, in which the solid polymer product suspended and transported.

Polymerization is performed, as a rule, at temperatures in the range from 50 to 125 C and under absolute pressures in the range from 1 to 100 bar. Used catalyst can be any catalyst used, as a rule, for the polymerization of olefins, such as catalysts of chromium oxide, Ziegler-Natta or type.

In many systems used reactors circulation, which are characterized by continuous tubular design, including at least two, for example four, vertical sections and at least two, for example four, horizontal section. Heat polymerization, as a rule, consider using indirect exchange with a cooling medium, preferably with water, shirts, others at least part of the tube reactor circulation. The volume of each reactor circulation system can vary, but usually it is in the interval from 10 to 200 m 3 , more typically 50 to 120 m 3 . Reactors with a circulation of applied during the implementation of this invention belong to this generic type.

As a rule, in the process of suspension polymerization receiving, for example, polyethylene suspension in the reactor usually includes powder polymer hydrocarbon diluent (thinners), (with) monomer [() (monomers)], catalyst, chain of agents such as hydrogen and other reactor additives. In particular, the suspension usually consists of 20 to 75, preferably from 30 to 70%. (in terms of the total weight of suspension) of powder polymer and from 80 to 25, preferably 70 to 30 wt.% (in terms of the total weight of suspension) suspension environment, where the liquid environment is the combination of all the components of the fluid in the reactor, and it usually involves thinner, monomer and supplements; diluent may be inert diluent or they can be thinner, particularly liquid monomer, where the underlying is an inert diluent diluent monomer is usually from 2 to 20, preferably 4 to 10 wt.%, the suspension.

The suspension is pumped through relatively infinite contour reaction system at speeds of fluid sufficient to save the polymer in suspension in the suspended condition and maintain acceptable concentration gradients and content of solid particles in the transverse section. Suspension is withdrawn from reactor containing polymer, together with reagents and inert hydrocarbons, which all consist mainly of inert diluent and unreacted monomer. Received a suspension, including polymer and thinner, and in most cases catalyst, monomer and , can be deleted periodically or continuously, not necessarily using concentrating device such as a hydrocyclones and vertical tanks, in order to minimize the amount of fluid discharged with polymer.

In polymerization processes composition of suspension is withdrawn from the end of the reactor depends on many factors, not counting the composition of the product, actually received by polymerization in the final reactor: it also depends on the target of the final product, reaction conditions and the relative proportions of products in any previous reactors. The reactionary conditions required for the final reactor, is also affected by the reactionary conditions in previous reactors, and the potential median effective concentration of substance in the subsequent reaction conditions has had a major impact performance of the catalyst in the previous reactors. Thus, the regulation of the composition of suspension withdrawn from the end of the reactor, as well as technological conditions are more complex than in the case of a single reactor.

One problem that can affect all of the above factors is the relative size of both reactors. There are many conflicting demands influencing optimization of the volume and size of both reactors. In order to cope not only with the polymer obtained in the reactor, but also with polymer carried from the previous reactor or reactors in the process of polymerization second and all subsequent reactors should be large enough. This means, apparently, that to keep a similar volume performance, the second and subsequent reactors should be more previous reactors. The disadvantage of this system, however, is that the required heat dissipation condition, often limiting performance, larger subsequent reactors higher than the required heat dissipation in the previous reactor. Accordingly, what should be the optimal ratio of the sizes of the reactor, not obvious. So, in particular, when the reactor system design for the process catalysts of different types (for example, Ziegler-Natta, chrome and/or ) or with catalytic system in which the necessary average effective concentration of substance or factor productivity between the reactors in different work modes varies significantly, the ideal combination of size reactors in each case is probably different, making it difficult for the choice of the ideal profile sizes. Profile effective concentration of substance in constant reaction conditions when changing between catalytic systems Ziegler-Natta, chrome, and/or on the basis of late transition metal also varies greatly.

However, when the present invention, it was established that the most optimal ratio of the sizes of the reactor is so, in which the second reactor at least 10% the first reactor.

Thus, the first object of the present invention is a process for obtaining multi-modal polyethylene in at least two reactors, connected in series, in which from 20 to 80 wt.% high-molecular (WFC) polymer get in suspension in the first reactor and from 20 up to 80 wt.% low molecular weight (NMC) polymer get in suspension in a second reactor in the presence of computational mathematics and Cybernetics of polymer, in which the concentration of solid particles in the second reactor of the NMC product, defined as the mass of the polymer, divided by the total weight of the suspension is at least 35 wt.% the most preferable is in the range from 45 to 60 wt.%, and/or value of the ratio of the concentration of particulate matter in the first reactor to this indicator in the second the reactor is maintained below 1.0, preferably in the range from 0.6 to 0.8, and, moreover, in which the volume of the second reactor at least 10%, preferably at least 30%, and more preferably at least 50%more than the amount of the first reactor.

When creating the present invention, it was established that the reactor system, in which the volume of the second reactor at least 10 percent of the amount of the first reactor creates an opportunity to reduce to a minimum the overall volume of reactors, while ensuring sufficient flexibility for manipulation with different working conditions and catalysts. In polymerization processes, in which the CMC polymer is produced in the first reactor catalytic activity in the first reactor is usually much higher than the activity of the catalyst in the second reactor. However, usually it is necessary to have relatively balanced in both reactors. When creating the present invention, it was established that this can be achieved in an effective and regulated by the increase in the length of stay in the second reactor of the NMC product relative to the first. This is done either by increase of the volume of the second (NMC) of the reactor on the first or/and increased concentration of solid particles in the second reactor relative to this indicator in the first.

In a preferred embodiment, the value of the ratio of length to diameter ratio L/D(1) of the first reactor CMC product exceeds this indicator of the second reactor of the NMC product L/D(2). More preferably L/D(1) at least 20% more L/D(2), and most preferably at least 30% more. As a rule, the value of the ratio L/D(1) the L/D(2) is greater than 1.5, it is most preferable to more than 2. The larger value L/D provides a greater surface area per unit volume, which, in turn, provides increased cooling capacity, as the capacity to cool the reactor depends on the area of the accessible surface, which can affect cooling. Thus, if the cooling requirement of both reactors are the same, larger reactor NMC product may be a lower L/D, than a smaller reactor CMC product. This creates an opportunity to balance the capacity of each reactor to while also minimizing the total volume of the reactor.

In General in a preferred embodiment, the value of the ratio of length to diameter (L/D) of the first reactor CMC product exceeds 500, preferably in the range of 750 to 3000, and it is most preferable to exceed 800, for example is from 800 to 1500. Usually the preferred option value of the ratio of length to diameter (L/D) of the second reactor of the NMC product exceeds 200, preferably from 200 to 1000 and most preferably from 250 to 750, for example from 300 to 550.

Usually each reactor has an internal volume of more than 10 m 3 , more commonly, more than 25 m 3 , in particular more than 50 m 3 . As a rule, he is in the range from 75 to 200 m 3 , and more specifically from 100 to 175 m 3 .

Preserving the value of the relationship of concentrations of particulate matter in the first reactor to this indicator in the second reactor at the level of below 1.0, preferably in the range from 0.6 to 0.8, also promotes the preservation of the balance average effective concentration of substance between the two reactors in the target range. Particulate matter is the average mass of the polymer respect to the total mass of the suspension.

Generally the concentration of solid particles in the reactor CMC product is within the range from 20 to 50 wt.%, more preferably ranges from 25 to 35 wt.%. In this case, the preferred variant of solid particles transferred from the first reactor of the second reactor, concentrate using zone of sedimentation and/or hydro cyclone. To reduce the share of comonomer transferred to the subsequent reactor, before can be entered RSS free from comonomer thinner with increasing thus the density of the polymer, produced in the reactor NMC product.

In a preferred embodiment, the multi-modal polyethylene is shear ratio of at least 15, typically ranging from 15 to 50, and preferably in the range from 21 to 35. The concept of "shear ratio" is the ratio of the index of polyethylene melt under high loads, Б, to MI 5 polyethylene. Б and 5 MI determine, in accordance with ISO standard 1133 190 degrees With using loads respectively 21,6 and 5 kg 2 MI determine similarly, but with a load application of 2.16 kg

Б multi-modal polyethylene coming out of the second reactor, the preferred option is in the range from 1 to 100 g/10 min, and preferably in the range from 1 to 40 g/10 min

In one embodiment, the catalyst used for polymerization, represents a catalyst Ziegler-Natta. In this case, the preferential treatment of the NMC to the CMC polymer is 40:60 to 60:40.

In polymerization processes composition of suspension is withdrawn from the end of the reactor depends on many factors, not counting the composition of the product, actually received by polymerization in the final reactor; it also depends on the target of the final product, reaction conditions and the relative share of products of all the previous reactors. Mandatory reactionary conditions in the final reactor also depend on the reaction conditions in previous reactors, and the potential median effective concentration of substance in the subsequent reaction conditions has had a major impact performance of the catalyst in the previous reactors. In General it is necessary that the main part of the liquid components devoted to the polymer from the end of the reactor, separated in tank in the conditions of such a temperature and pressure, so they can be re- simple cooling without re-compression. The rest of the liquid components are not removed by this method is separated in the second tank, running a lower pressure, and in order to return in the process, they are necessary for compressing again. The advantage is that in the future in the present description is mentioned as a way to "medium pressure steam", is that for the re-condensing re-compressed must be only a small fraction of evaporated liquid components. In creating this invention was determined that due to the careful regulation of reaction conditions there is a possibility to guarantee that the implementation of the method of "steam Ironing medium pressure" allows to carry out the process without the need to re-compression of liquid evaporated in the first tank.

In a preferred embodiment of the invention suspension containing multi-modal polyethylene, are transferred from the second of the two reactors in the Stripping the tank, working in conditions of such pressure and temperature, due to which at least 50 mole %, preferably at least 80 mol %, more preferably 90 mol %, it is most preferable to 95 mole % of the liquid component of the suspension is withdrawn from boil off the tank in the form of steam. In this variant, preferably tank concentration of ingredients with molecular weight below 50, With light products , consistent with equation With lung products <7+0,07(40-T (c )+4,4(P-0.8)-7(C H2 /S E t ), where T c and P c mean temperature (OC) and in gauge pressure (MPa) at the place where couples, led out of the boil off the tank, condense, and With H2 and C Et denote the molar concentration in tank respectively hydrogen and ethylene. Execution of the invention contributes to the achievement of this minimizing the concentration of light products in the second reactor. Obviously, the concept of "first" and "second" reactors belong to the sequence of polymerization, regardless of polymer and in a reactor receive.

In a preferred embodiment, the concentration of ingredients with molecular weight below 50, suspension, coming in the Stripping the tank, regulate by regulating the concentration in the second reactor. Thus, the preferred variant of concentration in the second reactor components, with molecular weight below 50, also corresponds to an equation With lung products <7+0,07(40-T )+4,4(P-0.8)-7(H2 /With Et , where light products , With H2 and C Et in this case denote the concentrations of components with molecular weight below 50, hydrogen and ethylene in the second reactor, P s and T c have the above values. The more preferred variant of the concentration of components with molecular weight below 50, the second reactor is the same as the concentration of components with molecular weight below 50, arriving in the Stripping the tank.

It is generally preferable to the concentration of components with molecular weight below 50, which corresponded to an equation With a light products <7+0,07(40-T (c )+4,4(P-0.8)-7(H2 /Et ), where light products , H2 , C Et R c a T c are shown previously, and refer either to the second reactor, or to tank depends on the specific embodiment of the invention.

The present invention is especially applicable when the catalyst polymerization represents a catalyst Ziegler-Natta, mainly if the overall performance of the process is at least 10 kg polyethylene/g catalyst, preferably more than 15 kg polyethylene/g catalyst, it is most preferable to more than 20 kg polyethylene/g catalyst. If polymerization catalyst is a bis-Cf metallocene LLDPE catalyst, it is most preferable bis- (TGI) connection, the overall performance of the process in this case, the preferred option is at least 3 kg polyethylene/g catalyst, preferably more than 6 kg polyethylene/g catalyst, it is most preferable to more than 15 kg polyethylene/g catalyst. If polymerization catalyst is a mono-Cf metallocene LLDPE catalyst, it is most preferable (tert-)(tetramethyl-η 5-)-η 4 -1,3-pentadiene, the overall performance of the process in this case, the preferred option is at least 3 kg polyethylene/g catalyst, preferably more than 6 kg polyethylene/g catalyst, it is most preferable to more than 15 kg polyethylene/g catalyst.

To achieve the above ratio of average effective concentrations of substances it is preferable that the value of the ratio of ethylene concentration in a liquid (in mol %) in the second reactor to this indicator in the first reactor was 5 or less. In a preferred embodiment, the value of the ratio of the concentration of ethylene in the second reactor to this indicator in the first reactor is 3 or less, and more preferably 2.5 or less. In the most preferred variant requirements as the ratio of concentrations of ethylene, and the ratio of the average effective concentrations of substances jointly meet. Ethylene concentration in a liquid is calculated as the number of moles of ethylene, divided by the number of moles of all liquid components.

In a preferred embodiment, the actual concentration of ethylene in the second reactor is less than 8 mole %. However, to guarantee a satisfactory level of performance is also preferable to ethylene concentration exceeded 1,5 mole %, was preferable to more than 2 mole %. The concentration of hydrogen in the second reactor in preferred variant is less than 5 mole %, more preferably less than 3 mole %. The ratio of hydrogen to ethylene in preferred option is 0 to 0.5 mol/mol.

In a preferred embodiment, the temperature of the first reactor is maintained within the range from 60 to 80 degrees, preferably less than 75? C, as this may contribute to balancing the effective concentrations of substances between the reactors and relevant cooling abilities.

To improve the median effective concentration of substance it is possible to introduce additives, preferably in the reactor NMC product. Similarly, you can add suppressors of side products, preferably in the reactor NMC product. Additionally or alternatively to regulate the balance average effective concentrations of substances in the second reactor can be also added additional catalyst. During the work of the configuration CMC-NMC in a preferred embodiment, the application of tools for improving the effective concentration of substance in the reactor CMC product and configuration NMC-CMC avoid, it usually can be avoided, but you can use it to minimize the required concentration of monomers in the reactor CMC product. This reduces the subsequent energy needs degassing.

In all variants of execution of the invention advantage of the invention consists in the optimization of the reactor balance average effective concentrations of substances, volume performance and cooling requirements and at the same time minimizing the concentration of light products in tank, to avoid having to re-compression, leading to increased efficiency. Execution of the present invention can create the opportunity for the pursuit of efficiency values monomer less 1,015, usually less 1,01, and preferably less 1,006, even with the volume performance of at least 100 kg/m 3 /h, more preferably at least 150 kg/m 3 /h, it is most preferable to at least 200 kg/m 3 /h, in each reactor. 'Effectiveness monomer" means the mass ratio of consumed ethylene + to the obtained polymer.

In case when the catalyst used for the polymerization reaction, represents a catalyst Ziegler-Natta, it is preferable that the only means of improving the effective concentration of substance and suppressor of by-products used in the reactor NMC product. An example is the hydrocarbon, and more specifically formula SN x CL 4-x , where x represents an integer from 1 to 3. The most preferred is a chloroform, l 3 . The number of added hydrocarbon due to the amount of catalyst Ziegler-Natta, and the preferred option is where the value of the molar ratio of added reactor hydrocarbon added to the reactor titanium exceed 0.1, preferably in the range of 0.2 to 1. Application hydrocarbon especially necessary when you add it in combination with catalytic systems, where it improves the effective concentration of substance, and suppresses the education of ethane, in particular with the catalysts Ziegler-Natta. It is effective also in a reactor receive low molecular weight of the polymer, as shows the cumulative effect of increasing the effective concentration of substance and suppressing the formation of ethane. Education ethane is added to the concentrations of light reagents in the reactor, so that it becomes more difficult to maintain concentration of light products in the source material to boil off the tank below the level required according to the invention. Education ethane may be particularly significant in producing low-molecular polymers, especially if hydrogen is present. When getting low-molecular polymer in the second reactor is also especially it is necessary to increase the activity of the catalyst, because as the ageing of the catalyst, and a high concentration of hydrogen help to reduce curing activity. Halogenated hydrocarbons, such as chloroform, can, therefore, provide a double benefit: increased activity and minimization of the concentration of light products in the second reactor.

Reactor preferred type used for such processes of polymerization, is a reactor circulation, which is characterized by continuous tubular design, including at least two, for example four, vertical sections and at least two, for example four, horizontal section. Heat polymerization, as a rule, consider using indirect exchange with a cooling medium, preferably with water, shirts, others at least part of the tube reactor circulation. The volume of one reactor circulation in system can vary, but it usually is in the range from 10 to 200 m 3 . In a preferred embodiment, the reactor, used during the execution of the present invention is a reactor circulation.

Typical manometric pressure generated in the reactor circulation, are in the range from 0.1 to 10 MPa, preferably in the range from 3 to 5 MPa.

Method according to the invention applied with obtaining of compositions containing ethylene and copolymers. Ethylene copolymers, as a rule, include one or more alpha-olefins quantity which can reach up to 12% preferably from 0.5 to 6 wt.% for example approximately 1 wt.%.

Alpha- monomers, usually used in such reactions, represent one or more 1-olefins, containing up to 8 carbon atoms per molecule and no branching closer to the double bond, than in the 4th position. Typical examples include ethylene, propylene, butene-1, pentene-1, hexene-1, octene-1 and mixtures, such as ethylene and butene-1 or ethylene and hexene-1. Butene-1, pentene-1 and hexene-1 are especially preferred for copolymerization of ethylene.

In one embodiment, a polymer is a plastic resin that has a density greater 940 kg/m 3 and Б from 1 to 100 g/10 min and including 35 to 60 wt.% first polyethylene fraction of high-molecular weight, and from 40 to 65 wt.% the second polyethylene fraction of low-molecular-weight, and the first polyethylene fraction includes linear low density polyethylene, which has a density of up to 935 kg/m and Б less than 1 g/10 min, and the second polyethylene faction includes high-density polyethylene having a density of at least 960 kg/m 3 , preferably at least 965 kg/m 3 , and 2 MI greater than 100 g/10 min, and polyethylene resin.

In industrial settings a powder polymer is separated from the diluent so that the diluent is not exposed to contamination, allowing you to return thinner in the curing area with minimal clearance, if it was needed. Selection of powder polymer obtained according to the method of the present invention, of diluent may be, as a rule, carried out by any method known in the art; for example, it may involve either (I) the use of such vertical tanks continuous action that RSS suspension through a hole in them creates a zone in which the polymer particles may to some extent to settle of a diluent or (II) continuous removal of the product by one or several unloading of the aisle seat in the reactor circulation can be anywhere, but preferably near the subsequent end of the horizontal contour sections. Operation of the reactor of the big diameter with high concentration of solid particles in suspension minimizes the number of primary diluent allocated from path. The use of concentrating device for drainage of polymer suspensions, preferably hydrocyclones (single or placed in the case of multiple hydrocyclones concurrently or sequentially)additionally improves the extraction of diluent energy-efficient manner, because forgetting to a significant downward pressure and evaporation selected diluent. Another means of increasing the working window of the end of the reactor and the reduction of the concentration of the monomer is subjected to low pressure, to boil off the tank medium pressure is a higher concentration can easily condense components, for example, by adding before fresh or return in the process of diluent.

When the end reactor system is a reactor circulation, the pressure is taken away, and preferably concentrated, polymer suspensions before the introduction of the primary tank Stripping lower and, optionally, . preferred variant stream is heated after lowering the pressure. Due to the execution of the invention pair diluent and just monomer allocated in the primary tank can be fused without re-compression. Next, they usually return in the process of polymerization. As a rule, gauge pressure in the primary reservoir is from 0,5 to 2,5 MPa, preferably from 0,5 to 1,5 MPa. Solid particles isolated from primary boil off the tank is normally sent to the secondary Stripping the tank to remove residual volatile substances.

Method according to the invention relates to all of catalytic systems for the polymerization of olefins, especially to those who are selected from catalysts type, in particular those made of titanium, zirconium, or vanadium of thermally activated silicon dioxide, or inorganic printed on the media catalysts on the basis of chromium oxide and of catalysts type, and the is cyclopentadienyl compound transition metal, in particular of titanium or zirconium.

examples of catalysts type of connection, including transition metal selected from the group IIIB, IVB, VB or VIB the Periodic table of elements, magnesium and halogen obtained mixture of magnesium compounds connection with transition metal and connection. Halogen can optionally, form an integral part of magnesium compounds or compounds of transition metal.

Catalysts type can be a , activated or or ionizing agent, as set out, for example, in the EP 500944 AND (firm Mitsui Toatsu Chemicals).

Most preferred are catalysts type. Among them specific examples include at least one transition metal selected from the group IIIB, IVB, VB and VIB, magnesium, and at least one halogen. Good results were obtained with those that include:

from 10 to 30 wt.% transition metal, preferably 15 to 20 wt.%,

from 20 to 60 wt.% halogen, preferably from 30 to 50 wt.%,

from 0.5 to 20 wt.% magnesium, usually from 1 to 10 wt.%,

from 0,1 up to 10 wt.% aluminium, usually from 0.5 to 5 wt.% the rest is usually on the elements arising from products used for their preparation, in particular carbon, hydrogen and oxygen. Preferred transition metal and halogen are titanium and chlorine. The most preferable catalysts are characterized by the following composition:

transition metal: from 8 to 20 wt.%

magnesium content: from 3 to 15 wt.%

chlorine content: from 40 to 70%.

aluminium content: less than 5 wt.%

the residual content of organics: less than 40 percent by weight of

Processes of polymerization, especially catalyzed catalyst Ziegler, as a rule, spend in the presence of . There is a possibility to apply any known in the art, mainly connections, including at least one aluminium-carbon chemical bond, such as the optional halogenated connection, which may include oxygen, or item group I of the Periodic table of elements, and . Specific examples are, apparently, connection of , such as , , such as , - and-, such as , mono - and , such as , - and-, such as , and joins involving lithium, such as LiAl(C 2 H 5 ) 4 . Well suited compounds, mainly those which are not . Especially and .

In one particular embodiment, a catalyst used in this process represents a catalyst Ziegler-Natta, the mass ratio of the NMC to the CMC polymer is 40:60 to 60:40 and volumetric capacity (defined as the performance of the polymer in kg/h per unit volume of the reactor is at least 150, preferably at least 200, most preferably at least 250.

Preferred catalyst chrome basis includes printed on the media catalyst with the oxide of chromium, which has containing titanium dioxide carrier, for example composite bearer of silicon dioxide and titanium dioxide. Especially preferred catalyst chrome basis ranges from 0.5 to 5 wt.% chromium, preferably about 1 wt.% chromium, in particular by weight of 0.9% chromium, in terms of the mass of chromium-bearing catalysts. Media includes at least 2 wt.% titanium, preferably from about 2 to 3 wt.% titanium is more preferable to approximately 2.3% Mas. titanium, in terms of the mass of chromium-bearing catalysts. Catalyst chrome basis may have a specific surface area from 200 to 700 m 2 /g, preferably from 400 to 550 m 2 /g, and volume porosity more than 2 l/g, preferably from 2 to 3 l/year of Catalyst on chrome base can be used in combination with activators, such as metal-organic compounds of aluminium or boron. Preferred are compounds such as , which alkyl chain include up to 20 carbon atoms. Especially preferable .

If the catalyst is a metallocene LLDPE catalyst, in the preferred version, it includes (TGI) connection. Preferred catalytic system includes (a) metallocene LLDPE catalytic component containing connection with the General formula (IndH 4 ) 2 R MQ 2 , in which all the IndH 4 are the same or different, and denote or substituted , R denotes the bridge, which includes 1-4 radical, or silicon, or , or , or amine radical, and the bridge replaced or not replaced, M denotes the metal-group IV or vanadium, and each Q denotes containing from 1 to 20 carbon atoms, or halogen; and (b) that activates the catalytic component. All connections can be replaced with the same or with honors from each other in one or several positions in ring, ring and ethylene bridge. Each substitution group can be independently selected from groups formula XR v , where X is chosen from elements of the group IVB, oxygen, and nitrogen, all R have the same or different values selected from a hydrogen or containing from 1 to 20 carbon atoms, a v+1 denotes the valence of X. In the preferred variant X denotes C. If ring substituted, his replacement groups should not be so bulky to influence the coordination of olefin monomers to metal Meters Preferred deputies in ring contain R as a hydrogen atom or CH 3 . More preferably at least one, and it is most preferable to both rings are not replaced. In particularly preferred variant of both not replaced. R" preferred variant indicates ethylene bridge, which is substituted or unaltered. Metal M the preferred option is a zirconium, hafnium or titanium, most preferably zirconium. All Q have the same or different values and can define or radical containing from 1 to 20 carbon atoms, or halo. Acceptable include aryl, alkyl, , or . Each Q the preferred option indicates halogen. Especially preferred connection is -(4,5,6,7-tetrahydro-1-).

In the method according to the invention of the first reactor of the serial number supplied in addition to and monomer, catalyst and , and each subsequent reactor supply at least monomer, particularly ethylene, and suspension caused by previous reactor of this series, and this mixture includes catalyst, and a mixture of polymers obtained in the previous reactor of such a series. As optional, to guide the second reactor and/or, if appropriate, in at least one of the following reactors fresh catalyst and/or . However, catalyst and preferable to enter only on the first reactor.

The table below contains curing conditions defined for the implementation of the present invention.

Metakaolin

Composition

Outer diameter of the reactor D

The length of the reactor L

L/D Ratio

Inner diameter of the reactor

Reactor capacity

%. the increase in the volume of the reactor

Max performance

Volumetric capacity

kg/m 3 /h

Conc. solid particles

Duration of stay

The density of the suspension

Efficiency

kg PE/gcata % mol. h

Conc. ethylene (C2)

The ratio L/D(R1) to the L/D(R2)

Feed speed catalyst

The ratio conc. particulate matter (R1:R2)

The effective ratio of R2:R1

The Ratio C2(R2):C2(R1)

1. The method of obtaining multi-modal polyethylene in at least two reactors in series, in the presence of catalysts for olefin polymerization, in which from 20 to 80 wt.% high-molecular (WFC) polymer get in suspension in the first reactor and from 20 up to 80 wt.% low molecular weight (NMC) polymer get in suspension in a second reactor in the presence of computational mathematics and Cybernetics of polymer, in which the concentration of solid particles in the second reactor of the NMC product, defined as the mass of the polymer, divided by the total weight of the suspension is at least 35 wt.% the most preferable is from 45 to 60 wt.%, and/or value of the ratio of the concentration of particulate matter in the first reactor to this indicator in the second reactor is maintained below 1.0, preferably in the range from 0,6 to 0.8, and, moreover, in which the volume of the second reactor at least 10%, preferably at least 30%, and more preferably at least 50 percent of the amount of the first reactor; the value of the ratio of average effective concentration of substance in the reactor NMC product to the median effective concentration of substance in the reactor CMC product ranges from 0.25 to 1.5, where the average effective concentration of substance in each reactor determine how the performance of polyethylene, obtained in the reactor (kg PE/h)/[ethylene concentration in the reactor (mol %) x duration of stay in the reactor (h) x speed catalyst injection into the reactor (g/h)], where the duration of stay defined as the mass of the polymer in the reactor (kg)/speed of removal of polymer from the reactor (kg/h); and in which the ratio of ethylene concentration in the liquid phase (mol %) in the second reactor to this indicator in the first reactor is 5 or less, the concentration of ethylene in the second reactor is less than 8 mol %, and the mean volumetric productivity (defined as the performance of the polymer in kg/h per unit volume of the reactor) in all the United reactors is more than 100 kg/m 3 /h

2. The method according to claim 1 in which the concentration of solid particles in the first reactor of CMC product is within the range from 20 to 50 wt.%, more preferably between 25 and 35 wt.%.

3. The method according to claim 1, wherein the average volumetric capacity (defined as the performance of the polymer in kg/h per unit volume of the reactor) in all the United reactors is more than 150 kg/m 3 /h, and preferably more than 200 kg/m 3 /h

4. The method according to claim 1, which used the catalyst is a catalyst Ziegler-Natta, the mass ratio of the NMC and Specialty polymer is 40:60 to 60:40 and volumetric capacity (defined as the performance of the polymer in kg/h per unit volume of the reactor) is equal to at least 150, preferably at least 200, most preferably at least 250.

5. The method according to claim 1, in which the ratio of length to diameter (L/D) of the first reactor CMC product is more than 500, preferably in the range of 750 to 3000, and it is most preferable to more than 800, for example, from 800 to 1500.

6. The method according to claim 1, in which the ratio of length to diameter (L/D) of the second reactor of the NMC product is more than 200, preferably from 200 to 1000 and most preferably from 250 to 750, for example from 300 to 550.

7. The method according to claim 1, in which the ratio of length to diameter of the first reactor CMC product, L/D(1), greater than this figure of the second reactor of the NMC product, L/D(2), and preferably at least 20% more.

8. The method according to claim 7, in which the ratio L/D(1) the L/D(2) is greater than 1.5, preferably more 2.

12. The method according to claim 1, wherein a suspension containing multi-modal polyethylene, are transferred from the second of the two reactors in the Stripping the tank, working in conditions of such pressure and temperature, due to which at least 50 mol %, preferably at least 80 mol %, more preferably 90 mol %, it is most preferable to 95 mol %, the liquid component of the suspension is withdrawn from boil off the tank in the form of steam.

13. The method according to paragraph 12, in which the concentration in the second reactor components, with molecular weight below 50, also corresponds to an equation With lung products <7+0,07(40-T )+4,4(R-0.8)-7(H2 /With Et , where light products , N2 , and C Et in this case denote the concentrations of components with molecular weight below 50, hydrogen and ethylene in the second reactor, T denotes the condensation temperature (OC) of the pair, a R C indicates the gauge pressure (MPa) at the place where couples, led out of the boil off the tank, condense.