A method of producing polymers of ethylene

 

(57) Abstract:

Describes a method of producing polymers of ethylene in the presence of a catalytic system of atalepaminupowik catalyst and socializaton in a multistage reaction sequence consisting of successive liquid-phase and gas-phase polymerization, comprising at least one continuous reaction sequence in which at the first stage, ethylene and, optionally, hydrogen and comonomer will polimerizuet in the reactor circulation in the environment of low-boiling hydrocarbons in the presence of atalepaminupowik catalyst and socializaton at a temperature of 75-100°C for at least 10 min, then the reaction mixture withdrawn from the reactor with a circulation of at least a significant part of the reaction medium is removed and the polymer is fed to the final stage where the polymerization is carried out in a gas-phase reactor in the presence of added ethylene and, optionally, hydrogen, comonomers and socialization. In the first stage, the residence time and reaction temperature are chosen so that the portion of the polymer of ethylene is obtained in the reactor circulation in the first stage polymerization, the final product of the method is 1-the Yu continue in the reactor circulation adding ethylene, hydrogen and, optionally, an inert hydrocarbon, comonomers and socializaton, where the residence time is at least 10 min, and the reactor circulation of the specified first stage polymerization, the melt index of the obtained polymer below the melt index of the polymer obtained in the reactor circulation of the second stage of the polymerization reaction, the ratio of the molecular weight of the polymer of ethylene, obtained in the first stage polymerization, the molecular weight of the final product is displayed with the specified end-stage polymerization is 0.25-5, and at the first stage polymerization, the polymerization conditions are chosen so that the melt index I2the obtained polymer of ethylene is between 0.01-50, and the second stage polymerization, the melt index I2is 10-2000. The technical result is to simplify the process and improve the quality of the target product. 8 C.p. f-crystals, 1 Il., table 4.

The invention relates to a method of producing polymers of ethylene, which has improved physical properties. In particular, the invention relates to a continuous multistage process for the preparation of polymers of ethylene, having a multimodal and/or broad molecular weight distribution. Megusta the Alov, having good resistance to cracking, to obtain a film of sorts, with good transparency and low content of gels, and to obtain the production method of pneumaturia, such as bottles.

Usually mechanical properties of plastic materials depend on molecular weight. The greater the molecular weight, the better the elasticity, softness and creep properties. In some applications, like the manufacture of films, bottles, cable coatings and pipe extrusion methods and pneumaturia, polyethylene having a high molecular weight distribution and a narrow molecular weight distribution is not suitable because of their poor flow characteristics and poor processing AIDS. That is why there are many different ways to obtain polyethylene having a broad molecular weight distribution.

One way of extending the molecular mass distribution is a mixture of polyethylene fractions of low and high molecular weight either mechanically or in solution. However, mechanical mixing is difficult to obtain a product that is fairly homogeneous. For mortar mixing expensive equipment is required, that is to alocate expansion of the molecular mass distribution by selecting the appropriate catalysts. However, the expansion of the molecular mass distribution in this way is quite limited. The catalytic activity also tends to rapidly falling, and therefore it will be necessary to remove catalyst residues from the product by washing, which makes the method uneconomical.

Two-stage expansion of the molecular mass distribution by using different concentrations of hydrogen at different stages are known or during polymerization at high hydrogen concentrations at the first stage and at low concentrations of hydrogen in the second stage, or Vice versa. At the first stage it is necessary to remove unreacted gases and hydrogen after the first stage. In the latter case, the standard Ziegler catalysts tend to lose their activity during polymerization at the first stage. The rate of polymerization, which is initially high, decreasing in the second stage due to reduced activity of the catalyst and high hydrogen concentrations. As a consequence, the residence time in the second reactor is much larger than in the first reactor. This means that at the second stage requires a larger reactor size, and is more difficult con is inih ways. Known two-stage methods are, for example, liquid-liquid-phase methods, vapor-phase and liquid-phase methods-gas-phase methods. The present invention relates to such a multi-stage method, where it is used as liquid-liquid and liquid-gas-phase polymerization. An example of liquid-liquid-phase polymerization is described, for example, in ZP 580930, where there are two arranged in series reactor with circulation. An example of liquid-gas-phase polymerization method shown in GB 1532231, US 4368291, US 4309521, US 4368304 and FI 86867. The closest analogue is the publication FI 86867, which corresponds to WO 92/12182 A1, class C 08 F 2/06, 23.07.92, 9 HP, which describes a method of producing polyethylene having a bimodal and/or broad molecular weight distribution, using a combination of reactor circulation and gas-phase reactor. In the first stage reactor circulation is ethylene, catalyst and socialization and inert low-boiling hydrocarbon, and preferably hydrogen, for polymerization of ethylene, and the residence time in the reactor is at least 10 minutes, at least a significant amount of reaction medium is separated and the polymer is removed in one or the kind or co monomer.

The present invention relates to a continuous multi-stage method for the polymerization of ethylene, which contains a row of three arranged in tandem polymerization reactors. It is well known and is offered in various publications using three-stage methods using solution, suspension or gas-phase polymerization. Typically, these publications provide an indication of that at all stages use the same type of polymerization, or what the next stage of polymerization are all in the same reactor. As an example of this type of publications, see U.S. patent 4336352, which mainly contains a polyethylene composition consisting of three different polyethylenes. In the publication, however, indicates the possibility of using different three-stage method for obtaining the composition. One presents alternative contains a sequence, where the first stage is polymerized polyethylene having a high average molecular weight, for example, 400000-6000000 and density between 940 and 980 kg/m3and the ratio of this fraction to the final product is 1-10%. In the next stage of polymerization is obtained polyethylene having an average malekin, having an average molecular weight 100000-1000000 and a density of 900 to 970 kg/m3. This publication describes that the polymerization can be carried out using the suspension polymerization, solution polymerization or gas phase polymerization, but does not indicate that at different stages of polymerization can be used in different ways polymerization. In the examples shown the suspension polymerization.

In General, it may be determined that any multi-stage method gives more or less the same type of products. In addition to the choice of catalyst, the properties of the product depend on the reaction conditions, which affect the activity and morphological properties of the catalysts, as well as on the morphological properties of the fractions of the product. The selection conditions are largely confined to the selected layout and used types of reactor. In particular, it should be noted that different types of end products, like product obtained by blow molding blanks, film and tubular products often require different types of properties, and the achievement of them all is difficult according to known techniques.

That is why there is a need for such multistage is a bookmark for a very wide choice of product.

In accordance with the invention found that the disadvantages of the well-known two - or multistage methods of polymerization of the polyethylene in an attempt to get the multimodal polyethylene and/or broad molecular weight distribution for a very wide range of product can be avoided by using a certain kind of combination of three consecutive reactors, each of which is the polymerization of ethylene under certain conditions.

Thus, the invention relates to a continuous method for producing polyethylene compositions in the presence of a catalytic system formed by polimerizuet ethylene catalyst and socialization, in a multistage reaction sequence, which includes liquid-phase and gas-phase polymerization. The method according to the invention contains at least one reaction sequence in which at the first stage, ethylene and, optionally, hydrogen and comonomer polymerized in the reactor circulation in the environment of low-boiling hydrocarbons in the presence of polymerizes ethylene catalyst and socializaton, and the time and temperature of reaction are such that the proportion of polymer of ethylene, or in the second stage, where polymerization proceeds in the reactor circulation adding ethylene, hydrogen and, optionally, an inert hydrocarbon, comonomers and socializaton, and the exposure time is not less than 10 min, the reaction mixture is removed from the reactor with circulation, and at least a substantial part of the reaction medium is removed, and the polymer is fed to the third stage where the polymerization is completed in the gas-phase reactor in the presence of added ethylene and, optionally, hydrogen, comonomers and socializaton.

Thus, the method according to the invention, from one point of view, can be considered as composed of three-stage sequence, formed, one after another, reactor circulation reactor with circulation and gas-phase reactor, each of which operates in certain conditions. This kind of three-stage sequence and its benefits have not been described in any of the early publications in this field.

The method according to the invention can, from another point of view, be considered as consisting of a two-step method consisting of a reactor with circulation and one or more sequential gas-phase reactors, so the power is projected, which is produced in a separate reactor with circulation under certain conditions and in a certain way.

According to the invention installed that work this way and the properties of the resulting polymer can be further improved when the polymer polymerized in another reactor with circulation under certain conditions, is fed into the reactor with circulation.

The method according to the invention provides several advantages. First, the method provides high flexibility in obtaining polymers with different molecular structure and the way of regulation of products to meet the requirements of different applications. Using the method can be optimized profiles the activity of the catalyst at various stages of the reaction. Next, using the method can be optimized morphological properties as the product is supplied in gas-phase reactor, and the final product. The use of a reactor with circulation enables high performance in a short time due to the good heat transfer and the effect of mixing, but the distribution of the time spent is wide. Usually, as a result, part of the catalyst is released almost unreacted, what, for example, the high content of gels. In the method according to the invention it is possible to obtain a significant narrowing of the distribution of the residence time of polymer particles, which gives a more homogeneous final products, since the polymer particles interact at various stages of the method with each other more or less the same way. Further, in the reactor with circulation, previous gas-phase reactor, the polymer fraction having a very high melt index, can be obtained by using large quantities of hydrogen. Known methods, on the other hand, are faced with operational challenges reactor with circulation due to the high content of hydrogen causing a marked increase in the fraction content of very fine particles, and additional difficulties in the operation of gas-phase reactor and processing systems and product deterioration of the properties of the final product. In the method according to the invention in a reactor with a circulation second stage of polymerization, however, served a polymer fraction with a relatively high molecular weight, therefore, in the reactor with a circulation second stage, the number fraction of very small particles increased slightly despite receiving at this stage factions, have, the reactor of the first stage is, in particular, reactor circulation, and the product fraction having the lowest amount of, is obtained in the first stage of the reaction. These and other advantages provided by the method, further described in the detailed description of the method.

Thus, the first stage of the method according to the invention is a polymerization reactor with circulation, where ethylene is polymerized in the environment of low-boiling hydrocarbons in the presence of catalytic systems for the polymerization of ethylene. Characteristic of this stage is that the reaction conditions are chosen in a certain way to achieve the specific properties of the product, and the fact that all of the reaction suspension is fed into the reactor with circulation of the second stage polymerization without the Department of environment and monomers or hydrogen.

Thus, the reaction conditions, in particular temperature and pressure, the residence time and, optionally, the amount of hydrogen that must be made are selected so that the amount of product obtained in the first stage reactor was within certain limits, and that the product had certain properties.

Firstly, it is essential for this stage is that poly is the final product. This makes it possible to obtain favorable conditions for the second stage polymerization in the reactor with circulation and additionally due to the fact that the required size of the reactor series reactor can be significantly less than in the sequential polymerization circulation. Additionally it is essential that the reactor of the first stage is, in particular, reactor circulation, resulting in the transport of product to the next reactor c circulation can only be performed on the basis of the differential pressure, and there is no need for transportation systems product like, for example, when the first reactor uses a gas-phase reactor.

Secondly, it is essential that the melt index of the polymer obtained in the reactor circulation of the first stage is lower than the melt index of the product obtained in the following reactor with circulation. This can be achieved by a well-known manner, while limiting the amount of hydrogen in the reactor, if at all he has. It is a special advantage in the case when the reactor with circulation of the second stage of the method used in very large quantities in the of OCI the melt index and low molecular weight. This type of polymer is relatively fragile, and hence in the reactor circulation of the second stage of polymerization can be obtained a higher number of fractions of very fine particles than is desirable, which is detrimental to the operation of gas-phase reactor and processing system of the product. In the method according to the invention these disadvantages, therefore, are excluded by the fact that in the reactor circulation of the first stage is obtained a polymer having a melt index lower than the melt index of the polymer obtained in the last reactor with circulation. This polymer contains better together and gives a smaller fraction of very small particles, and, upon application of this polymer in the last reactor with circulation polymerization proceeds without number of small particles, growing too fast, from the point of view of the final stages of the method.

Thus, in the first stage of the reaction, the reaction conditions are selected so that the melt index I2the obtained polymer is between 0.01 and 50, mostly between 0.05 and 10. This can be expressed according to the invention is also such that the molecular weight of the polymer is within certain limits. According to the invention the molecular weight of the polymer obtained in the Poland, than the molecular weight of the final product. Mainly, in the reactor with circulation of the first stage is obtained a polymer having a molecular weight of between 150,000, and 600000 and density of between 920 and 975 kg/m3mainly more than 940 kg/m3.

In the reactor with circulation of the first stage is possible, however, to obtain a polymer of ethylene having added to the polymerization reaction as co monomer a small amount of C4-8-alpha-olefin to obtain the density of the component in the interval 920-950 kg/m3, preferably in the range 920-945 kg/m3. This type of copolymer added to the fractional phase, formed from the reactor with circulation of the second stage gas-phase reactor of the third stage will influence mainly on the distribution of co monomer and molecular weight distribution of the final product, therefore, the properties of resistance to cracking of the final product will be particularly improved. This view of the final product is excellent, for example, for the purpose of receiving tubular products.

The co monomer used for obtaining the copolymer may be any C4-8-alpha-olefin or mixtures thereof. Considered comonomer can be selected from the group consisting of the ü selected in the range of 0.5-10 wt.%.

The reaction pressure in the reactor circulation of the first stage is selected, it is preferable, therefore, to be higher than in the last reactor with circulation. Thus, removal of the product from the reactor circulation is easy as possible, because the reaction mixture will generally be displayed to the last reactor with circulation from higher pressure to lower pressure. Thus, the reaction pressure can be selected within a relatively wide limits, for example, between 4000 and 9000 kPa, preferably between 5000 and 7000 kPa, provided however, that the pressure is higher than in the following reactor with circulation. Excretion to the next reactor with circulation can occur periodically or continuously.

The reaction temperature can be selected in a relatively large interval, however, taking into account restrictions on product features and product quantities.

Lower temperatures are used, mainly, in the first reactor with circulation than in the reactor circulation of the second stage, so that it is possible to maintain the catalyst activity at the required values. Thus, it is possible to select the reaction temperature is of the polymer in the reactor can be selected between 10 min and 2 h, preferably, between 0.5 and 1 h

In the reactor with circulation of the first stage can be used as the catalyst, any catalyst suitable for the production of ethylene polymers. These are, for example, Ziegler catalysts, which contain a transition metal from groups IV, V or VI of the Periodic system of elements, together with socialization, usually, with compositions alkylamine. Recommended transition metal is titanium, and the catalysts can be applied, for example, inorganic substrates, like silicon dioxide, aluminium oxide or silica - alumina. As catalysts it is possible to use new types of metallocene catalysts with socialization or without them.

It is further recommended that the entire quantity of catalyst was fed to the reactor with circulation of the reactor of the first stage polymerization, therefore, redundant catalysts are not served in the reactor circulation of the second stage and the following gas-phase reactor. Instead, you can submit acetalization or only in the preceding reactor with circulation, or in the last reactor, and socializaton served in various reactors, should not be the same. Ka is sakimay inert hydrocarbon fed into the reactor with circulation as a medium of polymerization. Examples of the corresponding hydrocarbons are aliphatic hydrocarbons such as propane, butane, pentane and hexane. The preferred hydrocarbons are, in particular, propane and isobutane. You can also use a mixture of one or more hydrocarbons mentioned above. The polymer suspension in an inert hydrocarbon, obtained in the reactor circulation, served without separation of inert components and monomers periodically or continuously directly into the last reactor with circulation, which operates at a lower pressure than the previous reactor with circulation. In some cases it may be useful if before feeding into the reactor with circulation of the second stage, at least part of the reaction medium as possible, hydrogen or used comonomer, is removed prior to feeding into the reactor with circulation of the second stage.

According to the invention the second and third stages of the method together form a partial stage, which consists of a reactor with circulation and consistent one or more gas-phase reactors according to Finnish patent FI 86867. This stage is obtained by the partial polymer of ethylene having a bimodal and/or broad molecular weight distribution, the second reactor (or reactors) - the fraction having a high molecular weight.

Thus, in a reactor with a circulation second stage served the reaction mixture from the first reactor with circulation, containing the active catalyst and socialization, inert environment, the monomer and, optionally, hydrogen. In addition, this reactor is fed with fresh monomer, hydrogen, optionally, comonomer and, optionally, socializaton. The reactor circulation may be of the traditional type, including means for supplying the various components of the power reactor, a means of circulating polymer-hydrocarbon suspension through the reactor, a means of heat transfer to remove the polymerization heat and remove the polymer slurry from the reactor and feed in the following gas-phase reactor.

As the polymerization medium is used, mainly, the same hydrocarbon as in the reactor circulation of the second stage, but not necessarily. Very suitable alternative means are, among others, propane and butane, especially propane.

The reaction mixture from the reaction mixture from the reactor with circulation of the first stage together with added fresh monomer, hydrogen, optionally, a co monomer form of particles in a hydrocarbon environment. Conditions of the reactor circulation are selected so that at least 20 wt. %, but preferably 40-90 wt.% all products polymerized in the second reactor with circulation. The temperature can be selected in the range of 75-110oC, mainly in the range of 85-100oC. the reactor Pressure is selected within 4000-9000 kPa, preferably, within 5000-6500 kPa, however, provided that the reaction pressure is below the pressure of the previous reactor with circulation. The residence time should be not less than 10 min, but preferably is within 1-2 hours a Molecular ratio of hydrogen to ethylene is selected depending on the desired quality of the final product, but when the bi-modal or tri-modal polyethylene it will be in the range of 0.1-1.

Special advantages are obtained, as described in the Finnish patent FI 86867, if the inert hydrocarbon is propane and the reaction is carried out in conditions where temperature and pressure are above the equivalent critical point of the reaction mixture, which consists of ethylene, propane, hydrogen and possibly co monomer, but the temperature, however, is below the melting point of the obtained polymer. That is why the temperature in the reactor is the use of supercritical propane phase it is possible to use higher concentrations of hydrogen, than you would in subcritical conditions. The solubility product is smaller, and the separation of a hydrocarbon (propane) and hydrogen via fast evaporation is easier. Besides, even if you use very high hydrogen concentration, the fraction of very fine particles that appear in this reactor circulation is lower, because the reactor is continuing the polymerization product obtained in the first reactor with circulation, and has the best consistency.

In this reactor with circulation obtained low-molecular-weight fraction having, preferably, the molecular weight of 5000-50000, molecular mass distribution MwMnbetween 2.5 and 9 and a melt index I2between 10 and 2000 g/10 minutes, More preferably, all of this component has a relatively high density, preferably between 950 and 980 kg/m3and a high melt index I2preferably, between 150 and 1500. In particular, when using propane as an inert hydrocarbon in the reactor with circulation and carrying out the polymerization in supercritical conditions in the reactor circulation it is possible to obtain a product having a very high index replicase to a very high level without the above operational problems of the reactor and disadvantages of morphology in the final product. The proportion of the product from the final product, derived from gas-phase reactor or recent gas-phase reactor is mainly 40-80%.

The reaction mixture was removed from this reactor circulation either continuously or intermittently in the usual way. Inert hydrocarbon mixture, the excess monomer and hydrogen are removed from the polymer particles in the traditional way, for example, the technology of rapid evaporation, and they can be recycled either in the same reactor with circulation or in the previous reactor circulation.

Concentrated polymer mixture is then fed into the gas-phase reactor. This reactor may be a conventional reactor with a fluidized bed, although can be used with other types of gas-phase reactors. In the reactor with a fluidized bed layer consists of well-educated and growing polymer particles, and more active catalyst, coming together with the polymer fraction. The layer is maintained in a fluidized state by the introduction of gaseous components, such as ethylene, with such a flow rate that causes particles to act as a fluid. Pseudoviruses gas may also contain inert gases-media such as the diluent, such as propane. In this case, the diluent may be injected in the form of a liquid or gas, or both. Adding liquid or gas can be produced in the lower part of the gas-phase reactor or directly into the polymer layer. In the latter case, you can apply a mixing device such as a mixer according to the application in Finnish patent 933073. This paper explains the mixing device for fluidized bed reactor, where at least part of the fluidized gas is introduced into the reactor through a channel in the mixer. This way you can enter in the polymer layer hydrocarbons in liquid form, so using their cooling effect.

Used gas-phase reactor can operate in the temperature interval between 60 and 115oC, preferably between 70 and 115oC, when the reaction pressure is between 1000 and 2500 kPa and the partial pressure of ethylene of between 200 and 2000 kPa. The molar ratio of hydrogen to ethylene is mainly lower than in the reactor circulation, for example, between 0 and 10 mol.%.

The product emerging from the gas-phase reactor, therefore, contains fractions coming out of the reactor with circulation of the first and second stages. Faction obrazovatelnie between 4.5 and 12. The proportion of this fraction from just the end product, preferably, is between 59 and 40 wt.%. The calculated molecular weight is obtained, for example, by calculation using gel chromatography to determine the molecular mass distributions for the fractions obtained in the reactor circulation, and in the final product.

The method according to the invention is not limited only option, in which there is only one gas-phase reactor in the above-described method. If necessary for the properties of this product or a process control can be consistently in the range of two or more gas-phase reactors.

The method according to the invention will be described hereinafter in more detail with reference to the drawing, which shows a schematic diagram of the method according to the invention. The reactor circulation of the first stage of polymerization indicated by the numeral 10. The catalyst capacity of the catalyst 11 is supplied via the supply line of the catalyst 13 through the feeder 12 into the reactor with circulation 10. The ethylene line 14, a low-boiling inert hydrocarbon medium line 15, optional hydrogen on the line 16 and the optional comonomer on line 17 are fed into the reactor with a circulation of 10 to line 18. is auctore circulation 10 the reaction mixture is circulated through the respective circulating device (shown), and at the same time the polymerization heat is removed by cooling the reactor or the reaction mixture through a cooling system (not shown).

From the reactor with a circulation of 10 polymer-hydrocarbon mixture is driven, preferably, directly into the reactor with circulation of the second stage 20 through line 21, or, optionally, using a periodically acting valve (not shown). In the reactor with a circulation of 20 polymerization continues adding diluent through line 22, ethylene through line 23, the hydrogen lines 24 and optionally the co monomer in the line 25 through line 26. In the reactor circuit 20 may also be added to the optional socialization in the usual way (not shown).

From the reactor with a circulation of 20 polymer-hydrocarbon mixture is fed through one or more exhaust valves 27 and line of transportation of the product 28 in the evaporative separator 30. Hydrocarbon medium is removed from the polymer particles, the residual monomer and hydrogen are removed from the evaporative separator 30 or line 31 in regenerating device (not shown) or back to the reactor with a circulation of 20 on line 26. Polymer particles are derived from the evaporative separator 30 on output line 32 in the gas phase reaction is maintained in a fluidized condition in the usual way when the circulation of gases, removed from the upper part of the reactor, through the compressor 42 and the heat exchanger (not shown) in the lower part of the reactor 40 in the usual way. The reactor, mainly, but not necessarily, equipped with a mixer (not shown). In the lower part of the reactor can be fed a well-known manner ethylene on line 45, not necessarily comonomer on line 46 and the hydrogen line 47. The product is removed from reactor 40 continuously or periodically transporting line 46 in the extraction system (not shown).

The invention is additionally illustrated by the following examples. In all the examples the catalyst is obtained in accordance with the application on Finnish patent 942949. As socializaton used triethylaluminium.

The first two examples show how the method of the invention improves the characteristics of the method (smaller fractions of very fine particles), as well as the characteristics of the material for the material processed by pneumoperitoneum (improved balance mass swelling-processability).

Example 1

In the reactor circulation, having a volume of 50 cm3and operating at a temperature of 60oC, is fed 2.7 kg/h of ethylene, 490 g/h of 1-butene, 0.5 g/h of hydrogen and 27 kg/h of propane. The catalyst on the substrate of the camping at a rate of 1.7 kg/H. The polymer suspension, leaving the first reactor with circulation, enters into another reactor with circulation, having a volume of 500 cm3and operating at a temperature of 95oC. In the reactor is added 30 kg/h of ethylene, 67 g/h of hydrogen and 28 kg/h of propane. The polyethylene is removed from the reactor with a rate of 28 kg/h of the melt Index of the material after the first reactor is equal 5-35 g/10 min. After the second reactor circulation is formed of 7.8% fraction of polymer particles having a diameter less than 100 microns. The melt index of the material after the second reactor is equal 300-800 g/10 min Hydrocarbons are removed from the polymer, which is served in a gas-phase reactor operating at a temperature of 75oC. the pressure in the reactor circulation is 6000-6600 kPa. In gas-phase reactor also introduced 48 kg/h of ethylene, 1.7 kg/h of 1-butene and 107 g/h of hydrogen. All of the gas-phase reactor output of 60 kg/h of polymer, having a density of 955 kg/m3and a melt index I2131 DG/min After gas-phase reactor has a 5.2% fraction of polymer particles having a diameter less than 100 microns. A sample of the polymer is granulated and processed by pneumoperitoneum in bottles. Massive swelling of the bottle is 99% compared to the industrial material-similar. Kolichesti melt flow. The material is easily recycled, as indicated on low pressure air forming machine, which equals 16200 kPa.

Example 2 (comparative)

In the reactor circulation, having a volume of 500 cm3and operating at a temperature of 95oC, served 29 kg/h of ethylene, 26 kg/h of propane and hydrogen so that its ratio to ethylene in the reaction mixture was 298 mol/KMOL. The catalyst on the substrate made of silicon oxide is introduced at a rate of 8.5 g/h as socializaton using triethylamine. The polyethylene is removed from the reactor with a rate of 27 kg/h After the second reactor with circulation, fraction of polymer particles having a diameter less than 100 microns, is equal to 27.2%. The pressure in the reactor circulation is 6000-6600 kPa. The hydrocarbons are removed from the polymer, which is served in a gas-phase reactor operating at a temperature of 75oC. In the reactor also introduces 45 kg/h of ethylene, 0.9 kg/h of 1-butene and 65 g/h of hydrogen. As a result of gas-phase reactor output 63 kg/h of polymer, having a density of 956,5 kg/m3and a melt index I2131 DG/min After gas-phase reactor has to 15.4% fraction of polymer particles with diameter less than 100 microns. A sample of the polymer is granulated and processed by pneumoperitoneum in bottles. Mass is conducted is low. However, the material is difficult for processing, as specified by the high pressure in the air forming machine (23800 kPa) (see tab. 1).

In examples 3 and 4 shows how the film properties (gels, mechanical properties and processability (stability of girder) can be improved by using the method of the invention.

Example 3

In the reactor circulation, having a volume of 50 cm3and operating at a temperature of 60oC, served 2.2 kg/h of ethylene, 431 g/h of 1-butene, 0.2 g/h of hydrogen and 28 kg/h of propane. The catalyst on a substrate of silicon dioxide is supplied with a speed of 6.5 g/h as socializaton using triethylamine. The polymer displayed continuously at the rate of 1.4 kg/h of the melt Index of the material after the first reactor is equal 5-35 g/10 min of Polymer suspension, derived from the first reactor with circulation, is introduced into another reactor with circulation, having a volume of 500 cm3and operating at a temperature of 85oC. In the second reactor circulation is added 33 kg/h of ethylene, 87 g/h of hydrogen, 4.6 kg/h of 1-butene and 42 kg/h of propane. The melt index of the material after the second reactor is equal 300-800 g/10 minutes, the Polyethylene is removed from the reactor with a rate of 31 kg/hour, a Pressure in the reactors with blood circulation to the temperature of the 75oC. In the reactor is also fed 49 kg/h of ethylene, 17 kg/h of 1-butene and 3,4 g/h of hydrogen. From gas-phase reactor output 70 kg/h of polymer, having a density of 923 kg/m3and a melt index I2117 DG/min Method is very stable, and run three weeks is carried out without difficulties. The polymer is granulated and processed by extrusion blown a 25-μm film on the pilot film line. The material is easily recycled, and the number of gels is low. Obtained by extrusion blown film is characterized by resistance to puncturing 1270

Example 4 (comparative)

In the reactor circulation, having a volume of 500 cm3and operating at a temperature of 80oC, served 23 kg/h of ethylene, 4.6 kg/h of 1-butene, 29 g/h of hydrogen and 29 kg/h of propane. The catalyst for polymerization on a substrate of silicon dioxide is supplied with a speed of 8.5 g/h as socializaton using triethylamine. The polymer displayed with a speed of 22 kg/hour, a Pressure in the reactor circulation is 6000-6600 kPa. The hydrocarbons are removed from the polymer, which is served in a gas-phase reactor operating at a temperature of 70oC. To the reactor was also introduced to 37.5 kg/h of ethylene, 14 kg/h of 1-butene and 7.5 g/h of hydrogen. From gas-phase reactor vyvoditsya method is stable. In particular, there are several failures during the run when transporting polymer from the reactor with circulation in gas-phase reactor. The polymer is granulated and processed by extrusion blown a 25-μm film on the pilot film line. The number of gels is very high (4900 1 m2). The strength of the perforation is equal to 83 g (see tab. 2).

Examples 5 and 6 illustrate the improvement of the way (less than a fraction of very small particles), and the number of gels in the product is reduced when using the location method of the invention. Besides, there are good mechanical properties of the film obtained by the combination of the method with circulation and gas-phase method.

Example 5

In the reactor circulation, having a volume of 50 cm3and operating at a temperature of 60oC, is fed 2.3 kg/h of ethylene, 430 g/h of 1-butene, 0.7 g/h of hydrogen and 22 kg/h of propane. The catalyst on the substrate made of silicon oxide is introduced at a rate of 11.5 g/h as socializaton using triethylamine. The polymer displayed continuously at the rate of 1.5 kg/h of the melt Index of the material after the first reactor is equal 5-35 g/10 min of Polymer slurry withdrawn from the first reactor with circulation, is introduced into another REO entered 31 kg/h of ethylene, 89 g/h of hydrogen and 28 kg/h of propane. The polyethylene is removed from the reactor with a rate of 27 kg/h After the second reactor with circulation, fraction of polymer particles having a diameter less than 100 microns, equal to 9.7 per cent. The melt index of the material after the second reactor is equal 300-800 g/10 min Hydrocarbons are removed from the polymer, which is served in a gas-phase reactor operating at a temperature of 75oC. To the reactor was also introduced to 57 kg/h of ethylene, 7 kg/h of 1-butene and 28 g/h of hydrogen. As a result of gas-phase reactor output 69 kg/h of polymer, having a density of 945 kg/m3and a melt index I21of 8.5 DG/min After gas-phase reactor, the fraction of polymer particles with diameter less than 100 microns is equal to 9.8 percent. The polymer is granulated and processed by extrusion blown film. The strength of the perforation of the film is equal to 240 g, and the content of the gels in the film is approximately 200 gels/m2.

Example 6 (comparative)

In the reactor circulation, having a volume of 500 cm3and operating at a temperature of 95oC, served 26 kg/h of ethylene, 38 g/h of hydrogen and 38 kg/h of propane. The catalyst on the substrate made of silicon oxide is introduced at a rate of 12.5 g/h as socializaton using triethylamine. The polymer is withdrawn from reactor SCM, - 26,6%. The pressure in the reactor circulation is 6000-6600 kPa. The hydrocarbons are removed from the polymer, which is served in a gas-phase reactor operating at a temperature of 75oC. In the reactor also introduces 45 kg/h of ethylene, 4 kg/h of 1-butene and 24 g/h of hydrogen. As a result of gas-phase reactor output 61 kg/h of polymer, having a density of 948 kg/m3and a melt index I217,2 DG/min After gas-phase reactor has 16,0% fraction of polymer particles having a diameter less than 100 microns. The polymer is granulated and processed into a film by extrusion-blow process. The strength of the perforation of the film is equal to 221 g, and the content of the gels in the film is approximately 600 gels/m2(see tab. 3).

Examples 7 and 8 is illustrated as using the method of the invention improves the characteristics of the method (less than a fraction of very small particles). At the same time very good mechanical characteristics of the pipe material, obtained by the combination of a circulating-gas-phase method, declining only slightly.

Example 7

In the reactor circulation, having a volume of 50 cm3and operating at a temperature of 70oC, is fed 1.5 kg/h of ethylene, 80 g/h of 1-butene, 0.7 g/h of hydrogen and 27 kg/h of propane. Catalysate is. is OLIMAR displayed with a rate of 0.9 kg/h of the melt Index of the material after the first reactor is equal 5-35 g/10 min of Polymer slurry withdrawn from the first reactor with circulation, is introduced into another reactor with circulation, having a volume of 500 cm3and operating at a temperature of 95oC. In the reactor is added 32 kg/h of ethylene, 75 g/h of hydrogen and 34 kg/h of propane. The polyethylene is removed from the reactor with a rate of 29 kg/h After the second reactor with circulation has 21% fraction of polymer particles having a diameter less than 100 microns. The melt index of the material after the second reactor is equal 300-800 g/10 minutes, the Pressure in the reactor circulation is 6000-6600 kPa. The hydrocarbons are removed from the polymer, which is served in a gas-phase reactor operating at a temperature of 75oC. In the reactor also introduces a 41 kg/h of ethylene 2,6 kg/h of 1-butene and 38 g/h of hydrogen. As a result of gas-phase reactor output 59 kg/h of polymer, having a density of 948 kg/m3and a melt index I5of 0.4 DG/min After gas-phase reactor, the fraction of polymer particles with diameter less than 100 microns is equal to 17.2%. The polymer is granulated and processed in the receiver. In the test with notched 4.6 MPa is obtained is more than 2000 hours In the test result when the pic is that for commercially available material-equivalent is equal to 350 hours in the same test).

Example 8 (comparative)

In the reactor circulation, having a volume of 500 cm3and operating at a temperature of 95oC, served 32 kg/h of ethylene, 60 g/h of hydrogen and 48 kg/h of propane. The catalyst on the substrate made of silicon oxide is introduced at a rate of 8.7 g/h as socializaton using triethylamine. The polyethylene is removed from the reactor with a rate of 31 kg/hours After reactor circulation has 34,6% fraction of polymer particles having a diameter less than 100 microns. The pressure in the reactor circulation is 6000-6600 kPa. The hydrocarbons are removed from the polymer, which is served in a gas-phase reactor operating at a temperature of 75oC. In the reactor also introduces a 47 kg/h of ethylene, 2.7 kg/h of 1-butene and 15 g/h of hydrogen. As a result of gas-phase reactor output 63 kg/h of polymer, having a density of 947,7 kg/m3and a melt index I50,37 DG/min After gas-phase reactor, the fraction of polymer particles having a diameter less than 100 microns, equal to 23.6%. The polymer is granulated and processed in the receiver. After tests at a constant tensile load, the result showing no gap after 700 h (see tab. 4).

1. A method of producing polymers of ethylene in the presence of a catalytic system of teleposta of the successive liquid-phase and gas-phase polymerization, including at least one continuous reaction sequence in which at the first stage, ethylene and, optionally, hydrogen and comonomer will polimerizuet in the reactor circulation in the environment of low-boiling hydrocarbons in the presence of atalepaminupowik catalyst and socializaton at a temperature of 75 - 100oC for at least 10 min, then the reaction mixture withdrawn from the reactor with a circulation of at least a significant part of the reaction medium is removed and the polymer is fed to the final stage where the polymerization is carried out in a gas-phase reactor in the presence of added ethylene and, optionally, hydrogen, comonomers and socialization, characterized in that in the first stage, the residence time and reaction temperature are chosen so that the amount of the polymer of ethylene is obtained in the reactor, from the end product of the method is 1 to 20 wt.%, the reaction mixture, derived from the first stage, is additionally fed to the second stage where the polymerization continues in the reactor circulation adding ethylene, hydrogen and, optionally, an inert hydrocarbon, comonomers and socializaton, where the residence time is at least 10 min, and the reactor circulation, is received in the reactor circulation last stage of polymerization, the ratio of the molecular weight of the polymer of ethylene, obtained in the first stage polymerization, the molecular weight of the final product is displayed with the specified end-stage polymerization is 0.25 - 5 and in the first stage polymerization, the polymerization conditions are chosen so that the melt index I2the obtained polymer of ethylene is from 0.01 to 50, and the second stage polymerization, the melt index I2is 10 to 2000.

2. The method according to p. 1, characterized in that the catalyst and socialization served only on the first stage of polymerization and, optionally, in a second reactor with circulation and/or gas-phase reactor.

3. The method according to any of the preceding paragraphs, characterized in that the reactor circulation in an inert hydrocarbon use propane and the reaction pressure and reaction temperature in the reactor circulation of the second stage are chosen so that the reaction liquid formed by the inert hydrocarbon monomer and hydrogen, is in a supercritical state.

4. The method according to any of the preceding paragraphs, characterized in that the reactor circulation with the first and the in the reactor with circulation of the second stage polymerization to obtain a polymer of ethylene having a molecular weight of 5,000 to 50,000 and a density of 950 to 980 kg/m3.

5. The method according to p. 1, characterized in that the reactor circulation of the first stage polymerization to obtain a polymer of ethylene having a molecular weight of less than 400000.

6. The method according to PP.1 to 3, characterized in that the first stage of polymerization in the reactor circulation serves as co monomer such number of C4-8alpha-olefins that the density of the product obtained in the reactor is 910 - 950 kg/m3.

7. The method according to p. 6, characterized in that comonomer selected from the group consisting of 1-butene, 1-hexane, 4-methyl-1-pentene, 1-octene or mixtures thereof.

8. The method according to any of the preceding paragraphs, characterized in that C4-8alpha-olefins serves as co monomer in the gas-phase reactor of the third stage polymerization.

9. The method according to any of the preceding paragraphs, characterized in that the propane is served in the gas-phase reactor through the mixer or in the liquid or gaseous state, or in both.

 

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