CS198185B2 - Process for preparing solid polymers of ethylene - Google Patents

Description

The production of ethylene polymers in the absence of low pressure solvents (about 0.28 to 2.45 MPa) in a fluidized bed reactor using various supported chromium catalysts is known from U.S. Patent Nos. 3,023,203, 3,687,920, 3,704,287 (3,709,853, Belgian Patent No. 773,050, and Dutch Patent Application 72-10,881. It is also disclosed in these publications that the ethylene polymers produced may be ethylene homopolymers or ethylene copolymers with one or more other arphins.

The aforementioned publications relate primarily to the preparation of polymers of high density ethylene, because, due to technical difficulties, it has hitherto not been possible in an industrially suitable manner to produce low and medium density ethylene polymers in low pressure fluidized bed reactors. Such a process would have to employ a catalyst capable of copolymerizing ethylene with other α-olefins to achieve the desired density range of the copolymer product, producing a polymer product having a particle size such that it can be readily fluidized in the reactor. fluidized bed; they must exhibit a high degree of productivity so that the catalyst residues in the polymer product are so small that they can be left in the product and there is no need to include a catalyst removal step in the production. The polymer product obtained by such a catalyst must be well formable in various applications, i.e. it must have a relatively broad range of melt index, and its low molecular weight content must be very low to comply with federal food and drug standards, in terms of extractable content (<5.5% w / w at 50 ° C in n-hexane, which is an important parameter in food applications. The catalyst needed for such a process must additionally be in solid form and provide copolymer products under operating conditions that can be easily achieved in an industrial fluidized bed reactor.

Attempts to use various known catalysts to obtain low to medium density ethylene polymers by an industrially applicable fluidized bed process have not been successful so far, since these catalysts do not possess the desired combination of properties described above. For example, certain Zleglerovy catalysts give products which have very low melt index (0.0 to 0.2 g s / 10 min) to ¹ poison and their productivity is relatively low, resulting in catalyst residue contents in the polymer, based on the transition metal, greater than 10 ppm. Thus, using Ziegler catalysts it is usually necessary to remove the polymer residues from the polymers.

Catalysts based on bis (cyclopentadienyl) chromium, described in U.S. Pat. Nos. 3,687,920, 3,70,853 and Belgian Patent No. 773,050, do not allow sufficient copolymerization of sufficient comonomers together with ethylene to obtain copolymers with a density below about 0.945 g / m ³ .

Although the group of supported silylchromate catalysts disclosed in U.S. Patent Nos. 3,324,095, 3,324,101 and 3,704,287 provide ethylene copolymers of relatively low density, some of these catalysts provide polymer products having a high particle size small particle size. which cannot be easily fluidized and / or which have a narrow melt index range (0.0 to 0.2 g / 10 min] or / and which have a relatively high content of n-hexane extractables.

The supported chromium oxide catalysts described in U.S. Patent Nos. 2,825,721 and 3,023,203 can be used to produce low and medium density ethylene copolymers when using high ratios of komonome.ru to ethylene in the monome stream. , handles. However, the copolymers produced have a relatively narrow melt index range (0.0 to 0.2 g / 10 min). Catalysts based on titanium-modified chromium oxide, supported as described in U.S. Pat. No. 3,622,521, provide copolymers with a substantially broader melt index range. Dutch Patent Application No. 72-10,881 discloses the use of fluoride and titanated chromium oxide catalysts for ethylene polymerization. Neither patent

However, U.S. Pat. No. 3,622,521 and Dutch Patent Application No. 72-10,881 do not disclose a practical method for producing low to medium density ethylene copolymers by an industrially suitable fluidized bed process.

Accordingly, it has not been possible to produce low to medium density ethylene polymers with a relatively wide melt index range of > 0.0 to about 2.0 g / 10 min with a relatively low content of extractables η-, hexane and a low catalyst residue content at relatively low temperatures and pressures in the absence of solvent by an industrially suitable fluidized bed process.

It has now unexpectedly been found that ethylene copolymers having a density of from about 0.900 to about 0.940 g / cm ³ and a melt index> 0.0 up to at least about 2.0 g / 10 min having a relatively low content of extractable substances can be used. hexane and catalyst residues, produced at relatively high productivity, suitable for industrial use, by a low pressure fluidized bed process, when ethylene is polymerized by the process of the invention with one or more C 3 -C 6 α-olefins in the presence of a supported catalyst having a certain specific particle size and containing a specific amount of chromium, titanium and optionally fluorine.

The present invention provides a process for the production of solid ethylene polymers having a density of 0.900 to 0.940 g / cm ³ melt index> 0.0 up to at least 2.0 g / 10 min under low pressure using a supported catalyst which has been activated to a air or an oxygen atmosphere at a temperature of 300 to 900 ° C containing, based on the total weight of the support and the catalyst,

0.05 to 3.0% by weight of chromium,

1.5 to 9.0% by weight of titanium and optionally up to 2.5% by weight of fluorine, wherein upon activation the chromium and titanium are contained in the catalyst in the form of oxides, characterized in that the ethylene is copolymerized with a sufficient amount of α-olefinic monomer 3 to 6 carbon atoms to achieve the desired density of the copolymer product in a fluid bed process at 30 to 105 ° C at a pressure of 1.03 to 6.87. MPa, at a gas mass flow rate through the bed of 1.5 to 10 times the minimum gas mass flow necessary for fluidization, by contacting the monomers with the fluidized particles of said supported catalyst catalyst having a mean particle diameter of 50 to 200 µm. ¹

The fluidized bed reactor system in which the catalyst system of the present invention may be used is shown in the attached figure.

By the process of the invention, copolymers can be produced containing a predominant molar proportion (> 85%) of ethylene and a minor molar proportion (< 15%) of one or more C3 to C6 olefins. These α-olefins are preferably propylene, 1-butene, 1-ipentene and 1-hexene.

Low-density polymers have a density of about 0.900 to 0.925 g / cm ^3, and high-density polymers have a density of about 0.926 to 0.940 g / cm ³ . The density of the polymer at a given level of melt index is controlled primarily by ¹ amount of C3 to C6 comonomers which is copolymerized with ethylene. In the absence of comonomers, ethylene would homopolymerize with the catalyst of the invention to form homopolymers having a density of about 5.95 g / cm ³ . Adding increasing amounts of comonomers to the polymers results in a decrease (substantially linear dependence) of the polymer density. Under the same reaction conditions, the amount of each; of the various C 3 to C 6 comonomers required to achieve the same result vary by <1 monomer to monomer.

Increasing the molar amounts of comonomers in the range C3> C4> Cs> Ce is required to achieve the same results, i.e., stiff density at a certain melt index.

The melt index of the polymers is dependent on its molecular weight. The relatively high molecular weight polymers have a relatively low melt index. Ultra-high molecular weight ethylene polymers have a high load melt index (HLMI) of about 0.0 g / 10 min and high molecular weight polymers have a high load melt index of about 0.0 to about 1, 0 g / 10 &lt; -1 >. Such high molecular weight polymers are difficult to mold in conventional injection molding machines and sometimes impossible at all.The copolymers produced by the process of the invention, on the other hand, are easy to mold in such equipment. a range of> 0.0 to at least about 2.0 g / 10 min, preferably in a range of about 0.1 to about 1.5 g / 10 min, and a melt flow index at higher load, also referred to as HLMI from about 1 to about 100 g / min The melt index of the polymers produced by the process of the invention is dependent on the combination of the polymerization reaction temperature, polymer density, and titanium content of the catalyst. increases with increasing polymerization temperature and / or increasing polymer density (i.e. with increasing the comonomer / ethylene ratio and / or increasing the titanium content of the catalyst.

The coDolymers produced by the process of the invention have a content of n-hexane extractables (at 50 ° C) of less than about 12% and preferably less than about 5.5%. As the fluorine content of the catalyst increases, the degree of polymerization of the C3 to C6 comonomers in the copolymer is improved. However, the increased fluorine content also tends to decrease the melt index of the polymers.

The copolymers produced by the process of the present invention contain an order of magnitude less than the amount of catalytic residues that are equivalent to about 10 ppm when converted to chromium metal. Preferably, the content of catalyst residues is less than about 3 ppm. Catalyst content is primarily a function of catalyst productivity and catalyst productivity is primarily chromium-dependent.

The copolymers of the invention have an average particle diameter of the order of about 0.13 to 1.52 mm, preferably 0.25 to 1.27 mm. The particle size is important in order to easily fluidize the polymer particles in the fluidized bed reactor described below.

The catalyst used in the process of the invention is a chromium oxide catalyst (CrOsJ), which is generally prepared by applying a suitable chromium compound, a titanium compound and a fluorine compound to a dried support, and then activating the resulting mixture by heating, air or air. an oxygen atmosphere at a temperature of about 300 to about 900%, preferably at a temperature of about 700 to 850 ^and C for at least 2 hours, preferably 5 to 15 hours. The chromium compound and the titanium compound are usually deposited on the support in the form of solutions and the fluorine compound are usually dry mixed with the titanium compound and the support on the carrier, using amounts of the individual components to achieve the desired chromium, titanium and fluorine content of the catalyst upon activation. and after activation, the catalyst is in the form of a powdery, free-flowing material 0.005 to 1% by weight, based on the amount of polymer produced.

The order of addition of the chlorine compound, the titanium compound and the fluorine compound to the carrier is not critical provided that all of the compounds are added prior to activation and that the carrier is dried before the titanium compound is added.

Upon activation of the supported catalyst, it contains the resulting system.

about 0.05 to 3.0, and preferably about 0.2 to 1.0 wt. of chromium (calculated as metallic chromium J, about 1.5 to 9.0 and preferably between 4.0 to 7.0% tactile titanium (calculated on metallic titanium J and

About 0.0 to about 2.5, preferably about 0.1 to 1.0 wt. fluorine (calculated as fluorine as element J, the percentages being based on the total weight of the carrier and the chromium, titanium and fluorine contained therein).

As chromium compounds, chromium oxide or any chromium compound which can be burned to chromium oxide under the activation conditions used can be used. At least a portion of the chromium must be in the hexavalent state in the resulting activated supported catalyst. Other chromium compounds which may be used in place of ky, s188185 chromium lichen are disclosed in U.S. Patent Nos. 2,825,721 and 3,622,521 and include, for example, chromium acetylacetonate, chromium nitrate, chromium acetate, chromium chloride, chromium sulfate and ammonium chromate. .

When the chromium compounds are applied to the carrier from solution, it is preferred to use water-soluble chromium compounds such as chromium oxide. However, chromium compounds soluble in organic solvents may also be used.

As the titanium compounds, any compounds which can be burned to titanium dioxide under the conditions of activation used can be used. Examples are those disclosed in U.S. Patent No. 3,622,521 and Dutch Patent Application No. 72-10,881. Particular examples of such compounds are those of formula (R ') _n Ti (OR') _m and (RO) _m. Ti (OR ') _n , wherein m is 1, 2, 3 or 4, n is 0, 1, 2 or 3, wherein the sum of man is 4,

R is a C 1 to C 12 alkyl, aryl or cycloalkyl group and combinations thereof such as aralkyl, alkaryl and the like,

R * cyclopentadienyl and C 2 to C 2 alkenyl such as ethylenyl, propenyl, isopropenyl, butenyl and the like and the formula

TiX 4 wherein X represents chloro, bromo, fluoro or iodo.

Titanium compounds thus defined include titanium tetrachloride, titanium tetraisopropoxide and titanium tetraibutoxide. The titanium compounds are more conveniently deposited on a carrier from solution in a hydrocarbon solvent.

The titanium content (such as Ti) in the catalyst relative to chromium (such as Cr 3, i.e. the molar ratio of these components is about 0.5 to 180, preferably about 4 to 35).

As fluorine compounds, hydrogen fluoride or any fluorine compound which does not convert to hydrogen fluoride under the activation conditions used may be used. Other fluorine compounds which can be used are disclosed in Dutch Patent Application No. 72-10881. Such compounds are, for example, ammonium hexafluorosilicate, ammonium tetrafluoroborltain, and ammonium hexafluoroborotate. Suitably the fluorine compounds are deposited on the support from an aqueous solution or by mixing the fluorine compounds with the other catalyst components in the dry state prior to activation.

The inorganic oxides which can be used as carriers in the catalyst systems of the invention are porous materials having a high specific surface area, i.e., a specific surface area of from about 50 to about 1000 m ² / g and a particle size of about 50 to 200 μτα. As inorganic oxides, silica, alumina, thorium oxide, zirconium oxide and other comparable inorganic oxides and mixtures of these oxides can be used.

The catalyst support which is already impregnated with a chromium and / or fluorine compound must be dried before it is contacted with the titanium compound. Drying is normally carried out by heating or drying the catalyst support with dry inert gas or dry air. It has been found that the drying temperature has a considerable effect on the molecular weight distribution on the melt index of the produced polymer. The preferred drying temperature is from 100 to 300 ° C.

Activation of the supported catalyst can be carried out at almost any temperature up to about its sintering temperature. By providing a stream of dry air or oxygen through the supported catalyst during activation, water is removed from the support. The activation time is sufficient when using well-dried air or oxygen, about 6 hours, etc. at a temperature of 300 to 900 ° C. At this temperature, the carrier has not yet sintered.

Any type of carrier may be used, but silicon dioxide in the form of microspheres having a specific surface area of 300 m ² / g, a pore diameter of about 20.0 nm and a mean particle size of about 70 µπί (WR Grace G-952) is preferred and about 30 m ^a / g, a pore diameter of about 16.0 nm, and a mean pore size of about 103 µm (WR Grace G-56).

The chromium deposited on the porous carrier having a high specific surface, described above, creates active sites on the surface and in the pores of the carrier. Although the actual process mechanism is not entirely clear, it is believed that polymers begin to grow both on the surface and in the pores of the supported catalyst. When the polymer formed in the pores of the supported catalyst in the fluidized bed is large enough, it breaks the support and thereby exposes the fresh active sites of the catalyst in the inner pores of the support. The supported catalyst can also divide many times during its life in the fluidized bed, thereby promoting the formation of low-catalyst polymers which do not need to be removed from the polymer particles. If the carrier particles are too large, they can resist rupture. This prevents the catalyst from splitting and is lost. In addition, large carrier particles can cause local overheating and so-called "hot spots" in the bed.

After formation of the activated catalyst, copolymerization can be performed. This is done by following the comonomer stream

818, & f? The above-described wash bed reactor is contacted with a catalytically effective amount of catalyst at a temperature and pressure sufficient to initiate polymerization, substantially in the absence of catalytic catalysts. poisons such as moisture, oxygen, oxide, carbon monoxide. and acetylene. The catalyst according to the invention can be used. ·. ·. use · in; up to about 200ppm carbon dioxide;

To achieve the required range of density; copolymers, it is necessary to copolymerize with ethylene sufficient. a plurality of carbon chain comonomers having 3 or more carbon atoms to provide a C 6 to C 6 comonomer content in the polymer of up to 15 mole% The amount of comonomer required to achieve this result It depends on the particular comonomer or comonomer used. and -on-content, fluoride -v, catalysts. zátoru. •Increase; content of 'fluoride v-. they improve somewhat the comonomer build-up. In addition, the various comonomers to be considered have, using the catalysts according to the invention, various copolymerization parameters with n-ethylene. " OF . for this reason, the amount of comonomer used in the stream. mo-. -. monomer ramps fed to the reactor. it also livel; dependence on and reactivity of the como-mer. ·. ·>, ..

The following table lists several different comonomers which can be used for copolymerization with ethylene for the purpose of λ. Making polymers having a density within the desired range at any controlled melt flow index. On the one hand, the quantity is given. co-monomar., as required in copolymer; in order to achieve these properties, on the one hand, the necessary comonome concentration, ru v. mel. % in gas. the monomer stream which is dosed d0; reactor ;. n—

Komonpmer Mol. %.

propylene · ¹ 3,

1-butene · '- 2,

1-pentene ·. 2,

1-hexene 1.0

^ ^ Reakťínívj yatépiL fljuid ^ IK ^ i Iqžeip, KTEB: _(-i instance it can be used, II Implementation způsobu.podle ·, vynáleZjU, -is ilustrován- With OPR-1. -;

Reactor 10 consists of reaction zone 12. and from the speed limiting zone 14. Reaction-fire 1? It contains a vapor. Polymer particles, formed particles pq. · Interpolymer p -menší, množstvíkataíy atop fhpdi- ^ <·, zovaného-, kontinuálníip flow pplymep ^ hr <hydratable and (mgdifikajč®ích; _-;! Plynnýich- existing plants; í! Obstructions formed by the gas and to be gas is _{refilled; ?} can not recycle., in the ifeakč-zone. 'order, to maintain the fluidized bed in. the fluidized state, the mass flow rate must be higher .plynu bed, ihpdnOtqjíhe ^, - the value Ίηΐηϊ-- málníhp ,, i-flow required · Preferably, the mass flow rate of the gas is about 4.5 to about 1.0 x, higher, preferably about -3 to about 3.0, higher. The Gmf designation for the miniraceous mass flow rate is low for the fluidization of the fluidized bed (Gm1). Wen.-a - ·

Yu, &quot; Mechapips-q-foululizate &quot;, Chemical _; . _n Engineering, Progression Symposium Series, J Volume 62, pp. 100-111 (19 (56)) g.

It is important that the bed always contains “. particles which are formed by the formation of zinc _{; R} boron, sneezing places "a. ,, which by.jzaphycoygjý ADI STRH ,, buovaly, .práškovítý catalyst in the reaction _zone}. Upon commencement of operation, the polymerization zone is usually added to the reaction zone. -the part of the ipe over; gas flow starts. Such particles may be identical sej-yznikajícímt-after-lypie _RPNI-R, because q _{r s} O- be _Hou; (Differently when different ,,;, _{qdtahm> f} - "it is -vzniklého particles, a polymer, such as, 'Ehna in kcipqlymerú.j.hlQl, ® / o.potřebná.V" gaseous --- ,, '''' · up to 15 '- 6 to 30 ·' ·., Up to 12 6 to 25> - - - · / ·

9.0 i · 4 to. 18 »·

7,5 - - ý 3 to 15 »-k ··>.

In the end, the clay, uiz., is not able to obtain particles of the desired particle size. ,. t-bed.

The carrier katalyzáthr ipq _i) h? _T the heater Nu;,. Y, e, flpld-. Preferably, the bed is preferably in the bed _. By means of a random reading, 3 i under atmospheric pressure. SÍKU.

Fluidizape se ,. a range of yq, y y-sqkou, ryphlp-sti, gaseous cycle, said; ppΙΙζθ, through a bed, which is typically taller and higher than the velocity of the supplementary gases, the bed usually looks like a dense mass. · PP - hyblivýchi, particles flowing in y.pínpm .yí _;; - _r ru ... the resulting pphchodein, -plynu Tla-forged drop through the bed is ρονρέ Pehoé · 'pppěkud' .. ,,; higher non-z, w .- · 1ρζ'ρ - ;, divided, průřezeηρ.φ, the bed is, therefore, dependent on the geometry píp.- hpakťoru. '. _s.

Doplňoyapýi 'pjyn - SE- states dp <ložp ptejv,., Nou speed electrical · jpko is rychlost'odtahovápí delivery ,,, c ,, .. ppíymerního product _Slqže) it .., our letter ,; The flue gas is determined by the catalyst 46 disposed therein. nad- ipženj. The gas lysis determines the loss of soybeans _; p ,,; lynu ... who recykj.u.je ,, / and, according, the ".nastayuje accordingly, the composition of the make-up gas to -VR peakerp- ^{zópě.ůdTžel-0} composition, gaseous, Phij5 ^is substantially in a constant state. .

In order to zayuči, la For the full, floidizace ^ it is stated _{in the} characterized. . DO- reakt.pru _R &_{cyklov.aný.-gas; and} / or »/ ,,,;., also part -doiplňO'vap.éhp'.plynu příýpdeph Ϊ-Ρ ·;., / ložepi below. Nad příjvodem; Yippee. positioned, the gas distribution plate 20, which extends the fluidization of the bed ...

Part of the gas; current. _y Agu off their feed which is, in the bed -tvoří- reeykió _y.dný-7 // gases who! ry ,, OD- wadi of polymeračpí. zones preferably

198185 'that passes through zone 14, located above the bed, in which speed is reduced and entrained particles fall back into the bed. Particle separation may be aided by the inclusion of a cyclone 22, which may either be part of or outside the speed reducing zone 14. If necessary, the recycle gas can then be passed through a filter 24, which is adapted to separate small particles therein at high flow rates to prevent dust from depositing on the heat transfer surface and on the compressor sheets.

The recycle gas is then passed through a heat exchanger 26 where reaction heat is burned out before returning to the bed. By constantly removing the heat of reaction, there is no appreciable temperature gradient in the upper part of the bed. A temperature gradient exists in the lower 152 to 304 mm bed, between the inlet gas temperature and the rest of the bed temperature. It has been observed that the bed almost immediately adapts the temperature of the recycle gas above this bed to the bed zone temperature so that the bed temperature is substantially constant under steady state conditions. Before the recycle gas is introduced into the bottom of the reactor via the inlet 18 and the fluidized bed through the distributor plate 20, the recycle gas is compressed in the compressor 28. The compressor 28 may also be placed upstream of the heat exchanger 26 in the flow direction.

The distributor plate 20 plays an important role in the operation of the reactor. The fluidized bed contains both growing and formed polymer particles, talk catalyst particles. Since the polymer particles are hot and can be active, they must be prevented from settling, since if any calm mass is formed, the active catalyst contained in these particles could cause the reaction to continue and the particles would melt due to the heat generated. It is therefore important that the recycle gas is allowed to accompany the bed at a rate sufficient to fluidize the particles at the bottom of the bed. The bottom of the bed is formed by a separating plate 20 and may be a sieve, a plate with slits, a perforated plate, a plate with caps (analogous to the distillation column trays) and the like. All parts of the plate may be stationary or de-movable For example, the plate described in U.S. Pat. No. 3,219,792. Whatever the plate design, the plate must disperse the recycle gas between the particles at the bottom of the bed and maintain it in a fluidized state. The board also aims to support a quiet bed of resin particles when the reactor is not in operation. The movable portions of the plate may be used to extrude the polymer particles retained on or in the plate.

Hydrogen in the range of about 0.001 to about 10 moles per mole of ethylene and comonomer can be used as chain transfer agents in the polymerization of the invention.

Optionally, any gas inert to the catalyst and reactants may be present in the gas stream to control the temperature in the system.

The fluidized bed reactor must operate at a temperature below the sintering temperature of the polymer particles. In order to prevent sintering of the particles, the working temperature must be below the sintering temperature. For the production of ethylene copolymers according to the invention is preferably operated at a temperature of about 30 to about 105 ° C., most preferably at 75 to 95 ^Q C. Temperatures of about 75-95 ° C are used to prepare products having a density of about 0.900 to G ' 920 g / cm ³ and temperatures of about 85 to 100 ° C are used to produce products with a density of about 0.921 to 0.940 g / cm ³ .

The fluidized bed reactor is operated under pressure; up to about 7.0 MPa, preferably at a pressure of about 1.05 up to about 2.45 MPa, and when working at higher pressures in this range, heat transfer is facilitated, since an increase in pressure results in an increase in unit volume heat capacity gas.

The catalyst is injected into the bed at a rate equal to the rate of consumption by the inlet 39 located above the distributor plate 20. Preferably, the catalyst is injected into the bed from the side at about 1/4 to 3/4 of its height. An important feature of the invention is that the catalyst is infused at a point above the manifold plate. Since the catalysts used according to the invention are highly active, injection into the space below the manifold plate could result in polymerization being initiated at this point, which could eventually lead to clogging of the manifold plate. On the other hand, injecting the catalyst into the fluidized bed helps to distribute the catalyst in the bed and prevents the formation of sites with high catalyst concentration, which can lead to "hot spots".

An inert gas such as nitrogen is used to introduce the catalyst into the bed.

Bed productivity is controlled solely by the catalyst injection rate. Bed productivity can simply be increased by increasing the catalyst injection rate and reduced by reducing the catalyst injection rate.

Since any change in the rate of injection of the catalyst results in a change in the rate of reaction heat evolution, the temperature of the recycle gas is adjusted up or down to accommodate the rate of heat evolution. This ensures a substantially constant temperature in the bed. Both the fluidized bed and the recycle gas cooling system must, of course, be equipped with appropriate apparatus for detecting temperature changes in the bed and the cooling system so that the operator can appropriately adjust the recycle gas temperature.

Under a certain combination of operating conditions, the fluidized bed is maintained at substantially the same height by moving part of the bed as the product at the same rate as the particle formation rate of the polymer product. Since the rate of heat evolution is directly proportional to product formation, the measurement of the increase in gas temperature along the reactor (i.e. the temperature difference between the inlet gas temperature and the outgoing gas temperature) determines the rate of polymer particle formation at a constant gas velocity.

Preferably, the polymer product particles are collected continuously through a conduit 34 or near the distributor plate 20. The particles are collected in the form of a suspension with a portion of the gaseous stream that is vented prior to settling to prevent further polymerization and caking before the particles reach the zone. where they gather. The suspending gas can also be used to transfer the product from one reactor to another as already mentioned.

The polymer product particles are accounted for and preferably removed by means of two sequentially operated time-adjusted valves 36 and 38 between which a separation zone 40 is provided. When the valve 38 is closed, the valve 36 is opened so that the gas / product mixture passes through zone 40. valve 38 opens to transfer the product to the outer insulation zone. The valve 38 is then closed and closed until the next product withdrawal.

Finally, the filuid bed reactor is equipped with a suitable venting system that allows venting of the bed during start-up and shutdown. The reactor does not require the use of any mixing or wall scraping devices.

The supported catalyst system of the present invention provides a fluidized bed product with a mean particle size of between about 0.13 to 1.52 mm, preferably between about 0.26 to 1.27 mm, with the support catalyst residues in the polymer being unusually small.

The feed monomer gas stream optionally containing gaseous diluents is fed to the reactor at a yield per unit time and bed space of 32.2 to 161 kg / hxm ³ .

The following examples serve to illustrate the invention in more detail, but do not limit the scope of the invention in any way.

The properties of the polymers produced in the examples are determined by the following test methods:

Density

ASTM D-1505-plate was equilibrated for 1 hour at 100 ^Q C to approach equilibrium crystallinity.

Melt Flow Index (MI)

ASTM D-1038-Condition E. Measurements are carried out at 190 ° C, data in g per. 10 minutes.

Flow rate (melt flow index at higher load) (HLMI)

ASTM D-1238-Con.dition F. The measurement is performed using a tenfold load than the melt index.

v, - τ., xx x, flow rate

Flow Rate Ratio = -—, ----------- Melt Flow Index Productivity

A sample of the resin product is ashed and the weight% ash is determined, since the ash is essentially a supported catalyst. The productivity is therefore expressed in kg of polymer produced per kg of total catalyst consumed.

Substances extractable with n-hexane. The resin sample is gently compressed into a film, and in this form, extraction with n-hexane is carried out at 50 ° C for 4 hours.

Example 1 to 2 1

A. Preparation of catalysts

The catalysts used in Examples 1 to 21 were prepared as follows:

To a solution of the required amount of chromium trioxide in 3 liters of distilled water is added 500 g of porous silica as carrier having a particle size of 70 μπι and a specific surface area of about 300 mVg. The carrier, water and chromium oxide mixture is mixed and allowed to stand for about 15 minutes. It is then filtered to remove about 2200 to 2300 ml of the solution. The chromium-containing silica is then dried in a stream of nitrogen at 200 ° C for about 4 hours.

About 400 g of supported chromium trioxide is then suspended in about 2000 ml of dry isopentane and the desired amount of tetraisopropyl titanate is added to the suspension. The system is then thoroughly mixed and then isopentane is removed by heating the reaction vessel.

The dried substance is transferred to an activating heated vessel, the desired amount of ammonium hexafluorosilicate [(NH4) and SiF6] is added thereto, and the resulting mixture is mixed. Then, the system is heated under nitrogen at about 50 ° C for about 1 hour and then at about 150 for about 1 hour to ensure that all isopentane is removed and to slowly remove organic tetraisopropyl titanate residues without the risk of ignition. Then the nitrogen stream is replaced with a dry air stream and the catalyst system is activated for about 2 hours at 300 ° C and then for about 8 hotdirn at 750 or 825 ° C. The activated catalyst is then cooled with dry air (room temperature) to about 150 ° C and then further cooled from 150 ° C to room temperature with nitrogen (room temperature).

The amounts of chromium, titanium and fluorine compounds that are added to achieve the desired concentration of these elements in the activated catalyst are shown in the following table:

818157 8 f

Quantity (compounds ·: Quantity of element -> in% seam by weight%> in <activo ^: · <

added? carry the 'supported' catalyst - '

CrOj Chromium (as Cr) 0.8 0.4 0.6 0.3 0.53 0.26 0.33 0.17 -> ¹ 0.13 0.07 Ti (isopropyl D · - '' Titan (as TI) 35 5,6 · 28? 4,5 ¹ 25 · '· < 4.1 (NH4) 2 SiFe Fluorine (as F) 1.5 0.7 0.6 0,3 ^r ' ^:

B. Use of the catalyst in the ⁱ 'příkladečK' ^l l ^'i -to' 21

A series of 21 experiments is performed; Ethyl, n-butyl, butadiene polymer is added. Each reaction is carried out for 2 to 4 hours after equilibrium is reached in the second or both bed fluidization systems. One system, referred to as reactor A, bullshit, has already been described in connection; with picture. Its lower part is 3.05 meters high and its' inner diameter 'is ¹ ' 0.943 'm'. Hor-and the part to be highly> 4, '88 ^J áijejí -m 'inner' ma *? - · rate is 0.597 meters. The second system, the reactor has a place Bj * »· rtálevkovité upper part of the reactors often 'by vertical flanks ^{ί (} Ο '- height · 5.03 m av and inside -0 -343 m) The bottom part of the editor B has the same dimensions: as the bottom part of the reactor-A. Examples 1 to 3

Examples! -> up to 8 ^hours with provádějí- · I / 'm reaktoru- B přičemž- - speed gas? čtyřnásobkeha '* · Gmf and the pressure is 21 AFC Katalyzátory- použité- in these examples - were prepared (u above- ^Velim; undiluted manner? • After aktivaci- when e &W.ób--><Sahu každý- of the carrier catalysts 0 4 · hmoit.%> Gr, 4j5 wt:% · -TV and '* 0.3' -hmot: ¹ pr ^;

F. The other reaction conditions in Examples ¹ to 8 are shown in Table I below.

TABLE I,,

Example?.; Temperature, ° C, Molar Ratio Molar Ratio Yield of Peptide;

C4H8 / C2H4,. H2 / C2H4. ,,, bed times and space ·; i, .n kg / h / m ³ . . , _i; .

1 90 0,07 · 0,04 '; · 83.6 2 89 0.10 140,0 ¹ i 3. ^AND 90 0,10 ' - - 83.6 4: 90 0,09 · - 101.3 "' 5 90 0.11 ’ y - 109,4 · 6 ^Jr 95 · ^1.1 0,085 -. . 116.0 i · '' 7 95 0,07 ' 101,3 '- 8 ¹ 95 0,07 ' -. 116,0 /.· Co-polymers produced: in Examples ¹ ! to <i 5 have the properties indicated in table -11.-.-

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Examples 9 to 17

Examples 9 to 15 are carried out in reactor B and examples 16 and 17 in reactor A at a gas velocity equal to four times Gmf. The catalysts used in these examples were prepared as described above. After activation at 825 ° C, the supported catalysts contain the following amounts of individual elements:

TI: 4.1 or 5.6 wt. %

F: 0.6 or 1.5 wt. %

Cr: 0.4, 0.26, 0.17 or 0.07 wt. ° / o.

The differences between these catalysts and the other reaction conditions used in Examples 9 to 17 are shown in Table III below.

The copolymers produced in Examples 9 to 17 have the properties listed in Table IV.

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Example 18 to 21

Examples 18 to 21 are carried out in reactor B at an overpressure of 2.1 MPa and at a gas velocity equal to four times Gmf. The catalysts used in these examples were prepared as described above. After activation at 825 ^q C, each of the supported catalysts contains the following amounts of individual elements:

Cr: 0.4 wt.

Ti: 4.5 wt.

F: 0.3% wt.

The other reaction conditions used in Examples 18-21 are shown in Table V,

Example

TABLE V

Temperature [° C] Molar ratio

C4H8 / C2H4

Yield per unit of time and bed space [kg / h / m ³ ]

18 86 0.07 59.6 19 Dec 89 0.06 59.6 20 May 05 / 0,085 69.2 21 95 0.04 58.0

The copolymers produced in Examples 18 to 21 have the properties listed in Table VI.

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Examples 22 to 39

A. Preparation of the catalyst

The catalysts used in Examples 22 to 39 are prepared as the catalysts for Examples 1 to 21. Chromium sources are used as chromium sources, tetraisopropyl titanate as the titanium source, and ammonium hexafluorosilicate [(NH4ZiSiFe)] as the fluorine source when fluorine is part of the catalyst. however, fluorine-containing substances are not used in the preparation of the catalyst.

A porous silica having a particle size of about 70 µm and a specific surface area of about 300 m ² / g is used as carrier for all catalysts.

The catalysts for cases 22-31 were activated by heating to 750 ° C in dry air for about 8 hours and the catalysts for Examples 32-39 were activated by heating in dry air at 900 ° C for about hours. After activation, the catalysts contain varying amounts of chromium, titanium and optionally fluorine. These quantities are shown in Table VII.

B. Use of Catalysts in Examples 22-39

The individual catalysts were used in each experiment to copolymerize 1-butene with ethylene at 91 ° C in reactor A under pressure.

2.1 MPa and a gas velocity of about four times Gmf. The reactions are carried out using a molar ratio of C4H8 / C2H4 of about 0.080 ± ± 0.002 and with a yield per unit time and bed space ranging from

3.9 to 4.8 kg / h / m ³ . The exact values are given in Table VII below. Table VII also shows the catalyst productivity in each experiment. The various properties of the polymers produced are shown in Table VIII.

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TABLE VIII

Example

Product Properties Flow Rate Density (HLMI) * [g / cm ³ ] [g / 10 min] Extractable Content [%]

Average particle size (diameter) of granules of produced polymer [mm]

22nd 13.1 0.9248 4.9 0.810 23 15.2 0.9278 3.7 0,764 24 8.2 0.9230 4.9 0,863 25 ' 19.6 0.9260 4.3 0.715 26 15.3 0.9232 3.9 0,826 27 Mar: 13.5 0.9258 4.0 0,924 28 14.9 0.9235 3.0 0,918 29 26.4 0.9244 4.3 0,822 30 16.9 0.9231 5.3 1,008 31 18.3 0.9245 3.9 0,800 32 24.2 0.9260 3.8 0.812 33 26.4 0.9261 3.5 0,735 34 12.4 0.9200 5.6 1,015 35 17.8 0.9262 2.8 0,683 36! 1.9 0.9215 1.9 0,721 37 11.8 0.9256 2.4 0.579 38 18.2 0.9267 3.1 0,672! 39 • 1.8 0.9215 2.7 0.551

* Flow rate values correspond to melt index (MI) values ranging from 0.005 to 0.2 g / 10 min.

Claims (2)

PSEDMĚT A process for the production of solid ethylene polymers having a density of 0.900 to 0.940 g / cm ³ , a melt index> 0.0 up to at least 2.0 under low pressure using a supported catalyst which has been activated in air or in an oxygen atmosphere at a temperature of 300 to 900 ° C which contains, based on the total weight of the support and the catalyst, 0.05 to 3.0% by weight of chromium, 1.5 to 9.0% by weight of titanium and optionally up to 2.5% by weight of fluorine, wherein after activation the chromium and titanium are contained in the catalyst in the form of oxides, characterized in that the ethylene is copolymerized with a sufficient amount of α-olefinic SUMMARY OF THE INVENTION OF THE INVENTION OF THE INVENTION OF THE INVENTION OF THE INVENTION OF THE INVENTION OF THE INVENTION OF THE INVENTION of a C 3 -C 6 monomer in order to obtain the desired density of the copolymer product in a fluidized bed process at 30 to 105 ° C at a pressure of 1.03 to 6.87 MPa. 1.5 to 10 times the minimum gas mass flow rate required for fluidization by contacting the monomers with the fluidized particles of said supported catalyst having an average particle diameter of 50 to 200 µm. 2. The process of claim 1 wherein solid ethylene polymers are prepared at a temperature of from about 75 DEG to 100 DEG C. at a pressure of about 10 to about 20 psi at a gas mass flow rate through the bed of three to six times the minimum mass flow rate. gas necessary for fluidization: