JPS6258612B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention has a density of 0.958 to 0.972 and a density of 22 to 32
It involves producing a homopolymer having a melt flow ratio of . The relatively narrow molecular weight distribution of an ethylene homopolymer with a density of 0.96 and a melt index in the 5-50 range makes it useful in injection molding applications requiring excellent impact strength properties. Thus, an ethylene polymer having a density of 0.96 and a melt index of 20 can be produced using the catalyst and low pressure gas phase method described in US Pat. No. 3,023,203, US Pat. However, the polymers made using the supported chromium oxide, silyl chromate, and chromcene catalysts disclosed in these patents, respectively, have relatively broad molecular weight distributions, as evidenced by a melt flow ratio of 35. Therefore, there are significant limitations to the use of the polymers of this patent in injection molding applications requiring excellent impact strength properties. It would therefore be desirable to provide a catalyst that allows for the easy production by gas phase processes of ethylene polymers with relatively narrow molecular weight distributions. In order to be industrially useful in gas phase processes such as the fluidized bed process of US Pat. No. 3,709,853, US Pat. No. 4,003,712 and US Pat. must be a highly active catalyst. That is, the catalyst used is 1 lb (0.45
50000lb (22700Kg) per Kg) preferably
Must exhibit polymer productivity of 100,000 lb (45,400 Kg). This is so because such gas phase processes typically do not use any procedure to remove catalyst residues. Thus, the catalyst residue in the polymer must be very low so that it can remain in the polymer without causing any significant problems for the resin processor and/or end user. When highly active catalysts are successfully used in such fluidized bed processes, the heavy metal content of the resin is the major metal, on the order of 20 ppm at a productivity level of 50,000, <10 ppm at a productivity level of 100,000, and <10 ppm at a productivity level of 300,000. At the sexual level, it is around 3ppm. Low catalyst residue also means that the catalyst is made of chlorine-containing materials such as titanium chloride, magnesium chloride and/or aluminum chloride used in some so-called Ziegler or Ziegler-Natsuta catalysts. It becomes important when because,
This is because if the residual chlorine value in the molding resin is high, pitting or corrosion will occur on the metal surface of the molding device.
Therefore, if the residual Cl value is about 200 ppm, it cannot be used industrially. U.S. Pat. No. 3,989,881 discloses the use of highly active catalysts to produce ethylene polymers with a relatively narrow molecular weight distribution (Mw/Mn) of 2.7 to 3.1 under slurry polymerization conditions. However,
US Patent No. 4011382 and Belgian Patent No.
U.S. Pat.
Attempts were made to use catalysts similar to those described in No. 3,989,881, but these were all unsuccessful. Also, to avoid the use of solvents in the slurry catalyst system of US Pat. No. 3,989,881, the Ti/Mg-containing components were dried. However, this dry product was a viscous, gummy, pyrophoric composition that was not in a free flowing form and could not be easily fed to the reactor. Even when it was blended with silica to improve its fluidity and then loaded into the reactor, industrially acceptable results were not obtained. That is, the productivity of the catalyst was low, the catalyst was pyrophoric and difficult to handle, or the polymer product was obtained in the form of needles with very poor flow properties and difficult to flow. US Pat. No. 4,124,532 discloses the polymerization of ethylene and propylene using highly active catalysts. The catalyst consists of a complex which may contain magnesium and titanium. Such a complex consists of a halide MX ₂ (where M can be Mg) and a compound M'Y (where M' can be Ti and Y is a halogen or an organic group) in an electron donor compound. ) is prepared by reacting with after that,
The complex is isolated by crystallization, evaporation of the solvent or precipitation. Polymerization is carried out using this complex catalyst and an alkyl aluminum compound. However, US Pat. No. 4,124,532 does not disclose any particular technique or method of preparing the catalyst to achieve the desired results described in the present invention. Without this special technique, the U.S. patent
The use of the catalyst described in No. 4,124,532 does not result in an industrial fluidized bed process for producing polyethylene on a commercial basis. U.S. Pat. No. 3,922,322 and U.S. Pat. No. 4,035,560 describe the use of several Ti-Mg-containing catalysts to produce granular ethylene polymers in a gas-phase fluidized bed process under pressures <1000 psi (70.3 Kg/cm ² ). is disclosed. However, there are significant drawbacks to using such catalysts in these processes. According to the example of U.S. Pat. No. 3,922,322, the catalyst of that patent has a very high residual catalyst content, about 100 ppm.
yielding polymers containing more than 300 ppm of Ti and Cl. Furthermore, as disclosed in the examples of this US patent, the catalyst is used in the form of a prepolymer, so that the reactor must be fed with a very large volume of catalyst composition. Thus, the production and use of this catalyst requires the use of fairly large equipment to produce, store, and transport it. The catalyst of US Pat. No. 4,035,560 also clearly results in polymers with high residual catalyst, and the catalyst composition is clearly pyrophoric due to the type and amount of reducing agent used therein. However, if ethylene is homopolymerized in the presence of a highly active magnesium-titanium complex catalyst prepared as described below with an organoaluminium compound and an inert support material under specific activation conditions, a density range of 0.96 to 0.97 and a density range of 22 to 32 It has been unexpectedly discovered that ethylene homopolymers having a melt flow ratio and a fairly low residual catalyst can be produced industrially with fairly high productivity by a low pressure gas phase process. One object of the invention is to have a density of about 0.96 to 0.97;
It is an object of the present invention to provide a process for producing ethylene homopolymers having a melt flow ratio of about 22 to 32 and a relatively low amount of residual catalyst in a low pressure gas phase process with fairly high productivity. Another object of the present invention is to provide a method by which ethylene homopolymers useful for a variety of end uses can be readily produced. Still another object of the present invention is to provide various novel ethylene homopolymers and molded articles made therefrom. Hereinafter, preferred embodiments of the present invention will be explained. The desired ethylene homopolymers of the present invention having low melt flow ratios are suitable for low pressure gas phase polymerization when the monomer charge is polymerized under certain combined operating conditions as described below and in the presence of certain highly active catalysts as described below. It can be easily produced with relatively high productivity by fluidized bed reaction. Ethylene Homopolymer The present homopolymer has a melt flow ratio of 22-32 preferably 25-30. This melt flow ratio value is also another means of indicating the molecular weight distribution of the polymer. Thus, a melt flow ratio (MFR) in the range 22-32 corresponds to a Mw/Mn value in the range approximately 2.7-4.1, and an MFR in the range 25-30 corresponds to a Mw/Mn value in the range 2.8-3.6.
Corresponds to Mw/Mn. Homopolymer is 0.958~0.972 preferably 0.961~
It has a density of 0.968. The melt index of homopolymers varies depending on molecular weight. Relatively high molecular weight polymers have relatively low melt indexes. Ultra high molecular weight ethylene polymers have a High Loaded Melt Index (HLMI) of about 0.0, and very high molecular weight ethylene polymers have a High Loaded Melt Index (HLMI) of about 0.0 to 1.0. It is difficult, if not impossible, to mold such high molecular weight polymers with conventional injection molding equipment. On the other hand, the polymers produced by the method of the present invention can be easily molded in conventional equipment. It is 0.0~50 preferably 0.5~
Standard load melt index of 35 and 11 to 950
It has a high load melt index. The melt index of the polymers produced by the process of this invention is a combined function of the polymerization temperature of the reaction and the hydrogen/monomer ratio of the reaction system. Thus, the melt index can be increased by increasing the polymerization temperature and/or increasing the hydrogen/monomer ratio. The homopolymer of the present invention has an unsaturated group content of
1 per 1000 carbon atoms usually 0.1 to 0.3 C=
C and a cyclohexane extractable content of less than about 3% by weight, preferably less than about 2% by weight. The homopolymer of the present invention has a residual catalyst amount (ppm) converted to titanium metal, which is about more than 0 and less than 20 ppm at a productivity of 50,000, more than about 0 and less than 10 ppm at a productivity of 100,000, and
A productivity of 300,000 indicates more than 0 and less than 3 ppm. As for the Cl, Br or I residue, the homopolymers of the invention have a Cl, Br or I content depending on the Cl, Br or I content of the precursor. From the Ti/Cl, Br or I ratio of the initial precursor, the Cl, Br or I residue can be calculated from productivity information based only on the titanium residue. In most cases, the homopolymers of the present invention prepared using only the Cl-containing component of the catalyst system (Cl/Ti = 7) have a Cl residual of greater than 0 and less than 140 ppm at a productivity of 50,000, and 0 at a productivity of 100,000. It is possible to calculate a Cl content of more than 70 ppm, and a Cl content of more than 0 and less than 21 ppm at a productivity of 300,000. In the process of the invention, homopolymers are readily produced with productivity up to about 300,000. The homopolymer of the present invention has a diameter of about 0.005 to
0.06in (0.013~0.15cm) preferably about 0.02~
It is a particulate material with an average particle size on the order of 0.04 in (0.05-0.10 cm). Particle size is important to facilitate fluidization of the polymer particles in a fluidized bed reactor, as discussed below. The homopolymer of the present invention is about 18-32 lb/
^ft3 (288-513Kg/ ^m3 ) preferably 25-32lb/ ^ft3
It has a bulk density of (401 to 513 Kg/m ³ ). Highly active catalyst The compounds used to form the highly active catalyst used in the present invention include at least one titanium compound and at least one magnesium compound as defined below.
a species, at least one electron donor compound, at least one activator compound, and at least one inert carrier material. Titanium compounds have the structure Ti(OR) _a X _b . In the formula, R is a _C1 to _C14 aliphatic or aromatic hydrocarbon group or COR' (where R' is a _C1 to _C14 aliphatic or aromatic hydrocarbon group), and X is Cl, selected from the group consisting of Br, I or a mixture thereof, a is 0, 1 or 2, b is 2 to 4,
And a+b=3 or 4. Titanium compounds can be used separately or in their mixed forms, including TiCl ₃ , TiCl ₄ , Ti
(OC ₆ H ₅ ) Cl ₃ , Ti (OCOCH ₃ ) Cl ₃ and Ti
(OCOC ₆ H ₅ )Cl ₃ is included. Magnesium compounds have the structure MgX ₂ (where X is selected from the group consisting of Cl, Br, I, or mixtures thereof). Such magnesium compounds can be used individually or in their mixtures, including MgCl ₂ , MgBr ₂ and
MgI ₂ is included. Anhydrous _MgCl2 is a particularly preferred magnesium compound. When producing the catalyst used in the present invention, the amount of the magnesium compound used is about 0.5 to 56 mol, preferably about 1 to 10 mol, per 1 mol of the titanium compound. The titanium and magnesium compounds should be used in a form in which they are readily soluble in the electron donor compound. The electron donor compound will be explained below. The electron donor compound is a titanium compound and a magnesium compound that are partially to completely soluble at 25°C.
It is a liquid organic compound. Electron donor compounds are known per se and are otherwise known as Lewis bases. Electron donor compounds include alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers,
Included are cyclic ethers and aliphatic ketones.
Preferred examples of such electron donor compounds are:
Alkyl esters of _C1 - _C4 saturated aliphatic carboxylic acids, alkyl esters of _C7 - _C8 aromatic carboxylic acids, _C2 - _C8 preferably _C3 - _C4 aliphatic ethers,
_C3 - _C4 cyclic ethers, preferably _C4 cyclic mono- or diethers, _C3 - _C6 preferably _C3 - _C4 aliphatic ketones. The most preferred electron donor compounds include methyl formate, ethyl acetate, butyl acetate, ethyl ether, hexyl ether, tetrahydrofuran, dioxane, acetone and methyl isobutyl ketone. Electron donor compounds can be used individually or in their mixed form. The amount of electron donor compound used is approximately 2 per mole of Ti.
~85 moles, preferably about 3-10 moles. The activator compound has the structure Al(R″) _c X′ _d H _e (where X′ is Cl or OR and R″ and R
are the same or different _C1 - _C14 saturated hydrocarbon groups, d is 0-1.5, e is 1 or 0, and c+d+e=3). Such activator compounds can be used individually or in mixtures thereof, including Al
(C ₂ H ₅ ) ₃ , Al(C ₂ H ₅ ) ₂ Cl, Al(iso-C ₄ H ₉ ) ₃ , Al ₂
(C ₂ H ₅ ) ₃ Cl ₃ , Al(iso-C ₄ H ₉ ) ₂ H, Al(C ₆ H ₁₃ ) ₃ ,
Al( _C8H17 ) ₃ , Al( _C2H5 ) _2H and _{Al ( C2H5 ) 2}
(OC ₂ H ₅ ) is included. When activating the catalyst used in the present invention, the amount of activator compound used per 1 mole of titanium compound is 10 to
400 mol, preferably 10-100 mol. The support material is a porous solid particulate material that is inert to the other components of the catalyst composition and other active components of the reaction system. These carrier materials include inorganic materials such as silicon oxide and aluminum oxide, molecular sieves, and olefin polymers such as polyethylene. The carrier material ranges from 10 to 250
μ is preferably used in dry powder form with an average particle size of 50 to 150 μ. It is also preferably porous and has a surface area of 3 m ² /g, preferably 50 m ² /g. The carrier material should be dry, ie free of adsorbed water. Drying of the carrier material is carried out by heating it at a temperature of 600°C. Alternatively, the support material dried at a temperature of 200 DEG C. can be treated with about 1 to 8% by weight of one or more of the aluminum alkyl compounds described above. By modifying the support with such an aluminum alkyl compound, a highly active catalyst composition is obtained and the particle morphology of the ethylene polymer produced is improved. Production of Catalyst The catalyst used in the present invention is prepared by first preparing a precursor composition from a titanium compound, a magnesium compound, and an electron donor compound as described below, and then adding the precursor composition to a carrier material and an activator compound as described below. It is produced by processing in a one-stage process or a multi-stage process of two or more stages. The precursor composition is formed by dissolving the titanium compound and the magnesium compound in the electron donor compound at a temperature ranging from 20° C. to the boiling point of the compound. The titanium compound can be added to the electron donor compound before, after, or simultaneously with the addition of the magnesium compound. Dissolution of the titanium and magnesium compounds can be promoted by stirring and, in some cases, by refluxing both of these compounds in an electron donor compound. After dissolving the titanium and magnesium compounds, the precursor composition can be separated by precipitation or crystallization with a _C5 - _C8 aliphatic or aromatic hydrocarbon such as hexane, isopentane or benzene. The precipitated or crystallized precursor composition has an average particle size of 10-100 microns and a bulk density of 18-33 lb/ft3 (228-33 lb/ ^ft3) .
529 Kg/m ³ ) in the form of fine, free-flowing particles. The particle size of the precursor composition can be controlled by the crystallization rate or precipitation rate. When the precursor composition is prepared as described above, it has the formula Mg _n Ti ₁ (OR) _o X _p [ED] _q . In the formula, ED is an electron donor compound, m is 0.5-56, preferably 1.5-5, n is 0 or 1, p is 2-116, preferably ~14, and q is preferably 2-85. is 4 to 11, R is a _C1 to _C14 aliphatic or aromatic hydrocarbon group or COR' (where R' is a _C1 to _C14 aliphatic or aromatic hydrocarbon group), and X is Selected from the group consisting of Cl, Br, I, or a mixture thereof. The letter written at the bottom right of the element titanium (Ti) is the Arabic numeral 1. In the process of the invention, the polymerization activity of the fully activated catalyst is very high, so that it is necessary to dilute the precursor composition with a support material to effectively control the reaction rate. Dilution of the precursor composition can be accomplished prior to or concurrently with partially or fully activating the composition as described below. Additionally, the dilution of the precursor composition is
0.033 to 1, preferably 0.1 to 1 part by weight of carrier material
This is achieved by mechanically mixing 0.33 parts of precursor composition. For use in the method of the invention, the precursor composition must be fully or completely activated. That is, it must be treated with sufficient activator compound to convert the Ti atoms of the precursor composition to an active state. However, it has been found that the method of activating the catalyst is very critical for obtaining active substances even in the presence of an inert support, for example. Therefore, U.S. Patent No.
A method similar to that of No. 3989881, for example by adding to the precursor composition forming a hydrocarbon slurry the entire amount of reducing agent theoretically required to fully activate the catalyst and then drying it at a temperature between 20 and 80°C. Attempts have been made to activate the catalyst in a manner that facilitates its use in gas-phase processes by removing the solvent, but the resulting product cannot be used for industrial applications in gas-phase fluidized bed processes. The activity was not high enough. To prepare a useful catalyst, at least the final activation step is carried out in the absence of solvent, and the activation is carried out in such a manner that no further solvent is required to obtain a sufficiently active dry catalyst. I knew it was necessary to do it. Two methods have been developed to achieve such results. In one method, the precursor composition is fully activated in the absence of solvent by dry blending the precursor composition with an activator compound outside the reactor. In this dry blending method, it is preferable to use the active agent compound while impregnating the carrier material. However, this method produces >10 fully activated dry catalysts.
They are problematic in that they are pyrophoric when containing % by weight of activator compounds. Another and more preferred method of catalyst activation is to partially activate the precursor composition with an activator compound in a hydrocarbon slurry, dry out the hydrocarbon solvent, and partially activate the precursor composition outside the polymerization reactor. After complete activation of the precursor composition with the same or a different follow-up activator compound, the precursor composition is fed to the polymerization reactor. Thus, in the dry blending catalyst production method, a solid particulate precursor composition is added to a solid particulate porous carrier material on which an activator compound has been adsorbed and uniformly blended. The carrier material is then adsorbed with the activator compound from a solution of the compound in a hydrocarbon solvent such that 10-50% by weight of the activator compound is added to 90-50% by weight of the carrier material. The amounts of precursor composition, activator compound, and carrier material used are such that the desired Al/Ti molar ratio is obtained and the final composition has a precursor composition/carrier material weight ratio of less than 0.50, preferably less than 0.33. The amount should be as follows. The amount of support material is thus that amount necessary to dilute the catalyst activated by the material and control the polymerization activity of the catalyst in the reactor to the desired level. When the final composition contains >10% by weight of active agent compound, it is pyrophoric. The dry blending operation may be carried out at ambient temperature (25°C) or lower, while ensuring that the dry mixture is thoroughly agitated to avoid any heat build-up during the subsequent activation reaction (initial exothermic). Make it. The catalyst thus obtained is fully activated and can be fed to a polymerization reactor and used as is. It is a free flowing particulate material. In another, more preferred method of catalyst activation, activation is carried out in at least two steps. In the first step, the solid particulate precursor composition diluted with a carrier material is partially activated by reacting with sufficient activator compound to achieve a molar ratio of activator compound/Ti of 1 to 10:1, preferably 3 to 3. A 6:1 partially activated precursor composition is obtained. This partial activation reaction is preferably carried out in the form of a slurry in a hydrocarbon solvent, after which the product mixture is
The solvent is removed by drying at a temperature of 20-80°C, preferably 50-70°C. In this partial activation method, the activator compound can be used while being adsorbed onto the carrier material used for its dilution. The resulting product is a free-flowing solid particulate material that can be easily fed to a polymerization reactor. however,
Partially activated precursor compositions are at best weakly active as polymerization catalysts for the process of the invention. Thus, to make this partially activated precursor composition highly active for ethylene polymerization, additional activator compound is added to the polymerization reactor to completely complete the precursor composition within the reactor. Must be activated. Then,
This additional activator compound and partially activated precursor composition are preferably fed to the reactor through separate feed lines. Additional activator compound can be sprayed into the reactor in the form of a solution in a hydrocarbon solvent such as isopentane, hexane or mineral oil. This solution usually contains
2-30% by weight of activator compound is included. Also,
The activator compound can be added to the reactor in solid form by adsorbing it onto a carrier material. The carrier material typically contains 10-50% by weight for this purpose.
Activators included. The amount of activator compound added to the reactor is such that the amount of activator compound and titanium compound fed into the reactor together with the partially activated precursor composition is equal to the total Al/Ti moles. Ratio 10~400
The amount is preferably 5 to 60. Thus, the additional amount of activator compound charged into the reactor reacts with the titanium compound in the reactor and completely activates it. In continuous gas phase processes, such as the fluidized bed process described below, individual portions of the partially to fully activated precursor composition complete activation of the partially activated precursor composition during continuous polymerization. Additional amounts of individual portions of activator compound are continuously fed into the reactor along with individual portions of the activator compound as needed to replace active catalyst sites expended during the reaction process. Polymerization Reaction The polymerization reaction is carried out in the absence of moisture, oxygen, CO, _CO2 , and catalyst poisons such as acetylene by a gas phase method, such as in the fluidized bed described below, at a temperature sufficient to initiate the polymerization reaction. It is carried out by contacting a catalytically effective amount of a fully activated precursor composition (catalyst) with a stream of ethylene at pressure. A fluidized bed reaction system that can be used to carry out the present invention is illustrated in FIG. To explain this, the reactor 10 consists of a reaction zone 12 and a moderation zone 14. Reaction zone 12 contains growing polymer particles, forming polymer particles, and a small amount of polymer particles, fluidized by continuously passing a modifying polymerizable gas component and a recycle gas through the reaction zone in make-up feed manner. and catalyst particles. In order to maintain a vegetative fluidized bed, the mass flow rate of gas through the bed must exceed the minimum flow rate required for flow, preferably 1.5 to 10 times Gmf, more preferably 3 to 6 times Gmf. As used herein, Gmf refers to the minimum mass flow rate of gas required to achieve fluidization [C.
Y. Wen & Y. H. Yu, “Mechanics of Fluidization
(Mechanism of Fluidization)”, Chemical Engineering
Progress Symposium Series, Vol.62, p100~
111 (1966)]. It is essential that the layer always contain particles to prevent the formation of local "hot spots" and to confine the particulate catalyst to the reaction zone and to distribute it throughout the zone. At start-up, the reaction zone is usually charged with particulate polymeric base material before the gas flow begins. Such particulate polymer may be the same type as the polymer to be produced, or may be different. When the type is different, it is removed together with the desired polymer particles to be formed as the initial product. After all, the starting layer is
It is replaced by a fluidized bed of intended polymer particles. The partially to fully activated precursor composition (catalyst) used in the fluidized bed is preferably stored in a gas-sealed reservoir 32 in preparation for use. Thus, the gas is inert to the storage material, such as nitrogen or argon. Fluidization involves the use of a high flow rate (typically about 50 times the feed flow rate of make-up gas) into and through the bed.
This is achieved by circulating gas. A fluidized bed has the appearance of a dense growing particle body with a possible swirl-free flow created by passing gas gently through the bed (barcolation). The pressure drop across this layer is equal to or slightly greater than the mass of the layer divided by the cross-sectional area. It thus depends on the geometry of the reactor. Makeup gas is supplied to the bed at a flow rate equal to the flow rate at which the product polymer particles are removed. The composition of the make-up gas is determined by a gas analyzer 16 located above the layer.
Measured by This device measures the composition of the gas that is to be recycled. Accordingly, the makeup gas composition is adjusted to maintain an essentially steady state gas composition within the reaction zone. To ensure complete fluidization, the recycle gas and, if desired, a portion of the make-up gas are returned into the reactor from a point 18 located below the fluidized bed. Thus, a gas distribution plate 20 is present above the return point 18 to aid fluidization of the bed. The portion of the gas flow that does not react in the bed constitutes the circulating gas. This is preferably removed from the polymerization zone by passing it through a moderation zone 14 located above the layer, where the entrained particles are given the opportunity to fall back into the layer below. Particle return may be assisted by a cyclone 22 which may form part of the deceleration zone or may be located outside of it. When desired, the circulating gas is supplied at a high gas flow rate to prevent fines from contacting heat transfer surfaces or compressor blades.
It may be passed through a filtration device 24 designed to remove small particles. The circulating gas is then compressed in a compressor 25 and passed through a heat exchanger 26 where the heat of reaction is removed and then returned to the bed. Due to the constant removal of the heat of reaction, there does not seem to be any noticeable temperature gradient in the upper part of the layer. However, within the bottom 6-12 inches (15-30 cm) of the bed, a temperature gradient exists between the inlet gas temperature and the temperature of the remainder of the bed. The bed thus almost immediately adjusts the temperature of the circulating gas that has come above this bottom layer of the bed zone to make it similar to the temperature of the rest of the bed, thereby keeping it essentially isothermal under steady-state conditions. It has been observed to work. The recycle thus enters the reactor from the base 18 and is returned to the fluidized bed through the distribution plate 20. Compressor 25 can also be installed upstream of heat exchanger 26. When operating the reactor, the role played by the distribution plate 20 is important. The fluidized bed contains growing or forming particulate polymer particles and catalyst particles. When the polymer particles are hot and possibly in an active state, they must be prevented from settling. This is because if a stationary body is present, the active catalyst contained therein can continue to react and cause melting. It is therefore important to diffuse the circulating gas into the bed at a flow rate sufficient to maintain fluidization at the base of the bed. The distribution plate 20 serves this purpose, and can be a slotted sieve plate, a perforated plate, a foam plate or the like. All plate members are fixed or
It may also be of the movable type disclosed in No. 2298792. No matter what the design of the plate is,
It must disperse circulating gas into the particles at the base of the bed to keep them in a fluid state, and it must also function to support a static bed of resin particles when the reactor is not in operation. The movable member of the plate can be used to displace and displace any polymer particles that become trapped within or deposited on the plate. In the polymerization reaction of the present invention, hydrogen can be used as a chain transfer agent. The hydrogen/ethylene ratio used varies from about 0 to 2.0 moles of hydrogen per mole of ethylene monomer in the gas stream. In order to increase the melt index value of the homopolymer to be produced, structures Zn (R _a ), (R _b ) (where R _a
and R _b is the same or different C ₁ -C ₁₄ aliphatic or aromatic hydrocarbon group) can be used together with hydrogen with the catalyst of the present invention. This Zn compound is present in the gas flow inside the reactor.
0 to 50 moles, preferably 20 to 30 moles (as Zn) per mole of titanium compound (as Ti) in the vessel
used in quantity. In addition, this Zn compound is
Preferably in the form of a dilute solution (2-30% by weight) in a hydrocarbon solvent or in a solid diluent such as silica.
It is introduced into the reactor in adsorbed form at 50% by weight. These compositions are therefore prone to spontaneous combustion. The zinc compound may be added alone or together with a further portion of the activator compound. The activator compound is charged to the reactor from a device (not shown), for example near the dispenser 27, which supplies the compound to the hottest part of the gas circulation system. The gas stream may also include any gas that is inert to the catalyst and reactants. Preferably, the activator compound is added to the reaction system in the hottest part of the recycled gas stream. Thus, the line 27 downstream from the heat exchanger, e.g.
Preferably, it is added to the circulation line via a. It is essential to operate the fluidized bed reactor at a temperature below the sintering temperature of the polymer particles. Therefore, to ensure that sintering does not occur, a working temperature lower than the sintering temperature is desirable. To produce ethylene homopolymer by the method of the invention, 30 to
A working temperature of 115°C is preferred. To make products with a density higher than 0.961 and lower than 0.968, preferably 90
Temperatures of ~105°C are used. Fluidized bed reactors are operated at pressures up to 1000 psi (70.3 Kg/cm ² ), preferably between 150 and 350 psi.
(10.5-24.6Kg/ ^cm2 ). By using pressures at the higher end of this range, heat transfer is enhanced. This is because an increase in pressure increases the unit volume heat capacity of the gas. The partially to fully activated precursor composition is injected into the layer from a point 30 located above the distribution plate 20 at a flow rate equal to its consumption.
Injecting the catalyst from a point above the distribution plate is an important feature of the invention. Because the catalyst used in the practice of this invention is highly active, if a fully activated catalyst is injected into an area below the distribution plate, polymerization will begin there and eventually cause clogging of the distribution plate. become. Instead, injection into the vegetative layer helps distribute the catalyst throughout the layer and tends to eliminate the formation of localized areas of high catalyst concentration that can also cause the formation of "hot spots." conveying the partially to fully activated precursor composition and the required additional activator compound into the layer;
A gas inert to the catalyst, such as nitrogen or argon, is used. The rate of layer formation is controlled by the catalyst injection rate. The rate of formation of the bed can be increased by simply increasing the catalyst injection rate, and can be decreased by simply decreasing the catalyst injection rate. Since changing the catalyst injection rate also changes the amount of reaction heat generated, the temperature of the circulating gas is adjusted up or down to adjust this amount of heat. Thus, an essentially constant temperature is thereby ensured within the layer.
Also, complete mechanization of the fluidized bed and circulating gas cooling system is of course required to be able to detect any temperature changes within the bed so that the operator can adjust the temperature of the circulating gas accordingly. Under given combined operating conditions, the fluidized bed is maintained at an essentially constant height by withdrawing a portion of the bed as product at a rate equal to the production rate of the particulate polymer product. There is a direct relationship between the rate of heat generation and the rate of product formation, so when the gas velocity is held constant,
By measuring the temperature rise of the gas across the reactor (the difference between the temperature of the incoming gas and the temperature of the outgoing gas), the rate of production of particulate polymer is determined. Particulate polymer product is preferably continuously removed from a point 34 at or near distribution plate 20. The particles are then suspended in a portion of the gas stream and discharged before they settle, in order to prevent them from reaching their final collection zone and further polymerizing and sintering. This antisedimentation gas can also be used to transport the product from one reactor to another, as described above. Particulate polymer product is conveniently and advantageously withdrawn by sequential operation of a pair of timing valves 36 and 38 defining a segregation zone 40. valve 38
is closed while valve 36 is open and valve 36 is closed.
and zone 40 and discharge a plug of gas and product into zone 40, and then valve 36 is closed. Valve 38 is then opened to pump product to an external collection zone. Valve 38 is then closed in preparation for the next product recovery operation. Finally, the fluidized bed reactor is equipped with a suitable discharge system for discharging the bed during start-up and shutdown. Thus, this reactor does not require the use of stirring and/or wall scraping means. The supported highly active catalyst system of the present invention has a
0.06in (0.013~0.15cm) preferably 0.02~0.04in
(0.05-0.10 cm), and the amount of catalyst remaining therein appears to be usually low. The gaseous monomer stream with or without inert gas diluent is 2-10 lb/hr/ft ³ (32-160
Kg/hr/m ³ ) is fed to the reactor at a production rate per unit space (bed volume) time. As used herein, the term "virgin resin (or polymer)" means particulate polymer as it is recovered from the polymerization reactor. The following "Examples" are provided to illustrate the method of the invention, but are not intended to limit the scope of the invention. The properties of the polymers produced in these Examples were determined by the following test method:

【table】

[Table] Directly proportional to the sum concentration and extinction coefficient.
Ru. In addition, the extinction coefficient is calculated by RJde Kock et al.
Literature value〓J.Polymer Science, Part
B, 2, 339 (1964).
Example Preparation of Precursor Composition In 5 flasks equipped with a mechanical stirrer, anhydrous
MgCl ₂ 16.0g (0.168M) and pure tetrahydrofuran
850 ml was mixed under nitrogen. While stirring this mixture at room temperature (~25°C), add 13.05 g of TiCl ₄
(0.069M) was added dropwise. After the dropwise addition had cooled, the contents of the flask were heated to reflux for 0.5 to 1 hour to dissolve the solids. The system was cooled to room temperature and pure n-hexane 3 was added slowly over 15 minutes. A yellow solid precipitated. After decanting the supernatant, the solids were washed with 1×3 n-hexane. Strain the solids into a rotating evaporation flask.
Drying at 40-60°C yielded 55 g of solid precursor composition. Mg compound and/or Ti during separation of precursor composition
Since the compound may be impaired to some extent,
The Mg-Ti content may be analyzed at this point. The empirical formula used herein to record the precursor composition assumes that the Mg and Ti are still present in the compound form originally added to the electron donor compound and that other residual components of the precursor compound are is derived on the assumption that it depends on the electron donor compound. Analysis of the solid revealed that it contained 6.1% Mg and 4.9% Ti. This is TiMg _{2.45 Cl 8.9 ( THF} ) _{7.0 (} where
THF means tetrahydrofuran). Activation Methods Method A - This method involves multistage activation of precursor compositions. In this method, activation is carried out such that the precursor composition is only partially activated, after which the composition is introduced into a polymerization reactor in which the remainder of the activation is carried out. A mixing vessel or vessel is charged with the desired weight of dry, inert carrier material. In the "Example" described here, the amount of inert carrier is 500 g of silica and 1000 g of polyethylene carrier. The inert carrier material is then mixed with a sufficient amount of anhydrous aliphatic hydrocarbon diluent, such as isopentane, to form a slurry system of the inert carrier material. The amount of diluent required for this is typically
4 to 7 ml per gram of inert carrier. The desired weight of precursor composition is charged to the mixing vessel described above and thoroughly mixed with the slurry composition. The amount of precursor composition used in the "example" catalyst preparation method is between 80 and 135 g, and the elemental titanium content is 1 g of precursor composition.
1±0.1mM per sample. The desired amount of activator compound necessary to partially activate the precursor composition is added to the contents of the mixing vessel so that the precursor composition is partially activated. Depending on the amount of activator compound used at this time,
The Al/Ti ratio of the partially activated precursor composition is
10 to 400, preferably 10 to 100. The activator compound is added to the mixing vessel in the form of a solution comprising 20% by weight of the activator compound (triethylaluminum in the Example) in an inert aliphatic hydrocarbon solvent (hexane in the Example). Activation is accomplished by thoroughly mixing and contacting the activator compound with the precursor composition. All of the above work
It is carried out at room temperature under atmospheric pressure in an inert atmosphere. The resulting slurry is then heated to atmospheric pressure under a purge of dry inert gas such as nitrogen or argon.
Remove the hydrocarbon diluent by drying at a temperature of 60°C. This method usually requires 3 to 5 hours. The product is in the form of a drying, free-flowing particulate material in which the activated precursor composition is homogeneously blended into an inert carrier. The dry product is stored under inert gas. When feeding additional activator compound to the polymerization reactor of this "Method A" in order to fully activate the precursor composition, the compound is first adsorbed onto an inert support material such as silica or polyethylene. can be done. Alternatively, in a more preferred embodiment, the activator compound can be injected into the reaction zone as a dilute solution in a hydrocarbon solvent such as isopentane. When the activator compound is to be adsorbed onto a silica support, the two materials are mixed in a container containing 4 ml of isopentane per gram of support.
The resulting slurry was then heated to atmospheric pressure under a nitrogen purge,
The hydrocarbon diluent is removed by drying at a temperature of 65±10°C for 3-5 hours. When the activator compound is to be injected into the polymerization reaction system as a dilute solution, a concentration of 5 to 10% by weight is preferred. Regardless of the method used to introduce the activator compound into the polymerization reactor for the purpose of completing activation of the precursor composition, the activator compound increases the Al/Ti ratio in the polymerization reactor from 10 to 400. It is preferably added at a flow rate of about 10 to 100%. The silica was heated to 200°C for 4 hours before use.
Dry for an hour. Method B--In this method, complete activation of the precursor composition is accomplished by admixture contacting the precursor composition with an activator compound adsorbed on an inert carrier material. The activator compound is adsorbed onto the inert carrier material by first slurrying the activator compound with a carrier material in an inert hydrocarbon solvent and then drying the slurry to remove the solvent. A composition with an activator compound content of 10-50% by weight is obtained. Thus, pre-dehydrated (4 hours at 800°C) silica
Charge 500g to the mixing container. The desired amount of activator compound is then added to the vessel as a 20% by weight solution in a hydrocarbon solvent such as hexane and mixed (slurried) with the inert carrier in the vessel at atmospheric pressure and room temperature.
do. The solvent is removed by drying the resulting slurry at atmospheric pressure and 65±10° C. for 3 to 5 hours in a stream of dry, inert gas such as nitrogen. The dried composition is in the form of free-flowing particles having the dimensions of the carrier material. Approximately 500 g of the activator compound supported on this silica and dried (silica/activator compound = 50/50% by weight)
Add to the mixing container. Also, add the desired amount (80-135 g) of precursor composition to the mixing vessel. The materials are then thoroughly mixed under a dry inert gas such as nitrogen or argon at atmospheric pressure and room temperature for 1 to 3 hours. The resulting composition is 10-150μ
It is in the form of a physical mixture of dry, free-flowing particles having dimensions of the order of magnitude. During this mixing operation, the carrier-supported activator compound is brought into contact with the precursor composition and is fully activated. During the exothermic reaction that occurs, the temperature of the catalyst composition should not rise above 50°C to avoid any significant deactivation of the catalyst. The activated composition is Al/Ti
The ratio is 10 to 50. >10% by weight of this composition
activator compounds, it can become pyrophoric. Prior to reactor injection, it is stored under a dry inert gas such as nitrogen or argon. Examples 1-3 In each of these three examples, ethylene was homopolymerized using a catalyst formed as described above and activated as in Activation Method A above. The silica diluted precursor composition contained 18.4±1% by weight of precursor composition. In each case, the Al/Ti molar ratio of the partially activated precursor composition was 4.52±0.03. Complete activation of the precursor composition in the polymerization reactor is due to Al/
Triethylaluminum was adsorbed on silica so that the Ti molar ratio was 30 (weight ratio of both substances =
50/50). After reaching equilibrium, 3-4× G _n under a pressure of 300 psig (21 Kg/cm ² ) in a fluidized bed reactor system.
_f gas velocity, 3-6 lb/hr/ft ³ (48-96 Kg/hr/
Each reaction was carried out continuously for >1 hour with a production rate of m ² ) (layer space) per unit space time. The reaction system is as shown in the drawing. It is 10ft high (3.05
m), 13.5in (34.3cm) inner diameter lower area and 16ft height
(4.88 m), with an upper area of 23.5 in (59.7 cm) inside diameter. The table lists the _H2 /ethylene molar ratio and ethylene volume percent used in each of Examples 1-3, as well as various properties of the particulate polymer produced in each example.

TABLE Examples 4-16 In each of these series of 13 examples, ethylene was homopolymerized using a catalyst formed as described above and activated as in Activation Method A above. In each case, the partially activated precursor composition Al/Ti
The molar ratio was 4.71±0.01. Complete activation of the precursor composition in the polymerization reactor is carried out in the form of a 2.6-5 wt% isopentane solution such that the Al/Ti molar ratio of the fully activated catalyst in the vessel is 13-62. The experiment was carried out using triethylaluminum with the following properties. Each reaction was carried out as in Examples 1-3. The reaction conditions for Examples 4 to 16 are shown in the table below and are maintained in the reactor.
The Al/Ti molar ratio and the amount (wt%) of the precursor composition of the mixture obtained by diluting the precursor composition with silica are listed. The table also lists various properties of the polymers produced in Examples 4-16. In each of Examples 5, 6 and 9, diethylzinc was added to maintain a Zn/Ti ratio of 30 in the reactor.
It was added to the reactor as a 2.6% by weight solution in isopentane. The activator compound is also 2.6 in these examples.
It was added to the reactor as a wt% isopentane solution.

【table】

【table】 [Brief explanation of the drawing]

FIG. 1 is a flow sheet illustrating the method of the present invention. FIG. 2 shows a gas phase fluidized bed reactor in which the catalyst system of the present invention can be used. Explanations of the symbols representing the main parts in FIG. 2 are as follows. 10: reactor, 12: reaction zone, 14: deceleration zone, 16: gas analyzer, 18: gas introduction point,
20: Gas distribution plate, 22: Cyclone, 2
4: filtration device, 26: heat exchanger, 27: dispenser, 30: inert gas introduction point, 32: reservoir for impregnated precursor composition, 34: product discharge point.

Claims (1)

[Claims] 1. In ^the gas phase, Ti ₁ lb (0.45
A catalytic process for producing particulate ethylene homopolymers having a density of 0.958 to 0.972 and a melt flow ratio of 22 to 32 with a polymer productivity of greater than 50,000 lb (22,700 Kg) per kg (MgX ₂ (where X is Cl, At least one magnesium compound having the structure selected from the group consisting of _Br , I _, or a mixture thereof) and Ti( _OR ) _a group or COR′ (R′ is C ₁ ~
_C14 aliphatic or aromatic hydrocarbon group)
, a is 0 or 1, b is 2 to 4, and a + b = 3 or 4], and at least one titanium compound having the structure: The electron is formed by dissolving the liquid organic compound in at least one electron donor compound selected from the group consisting of alkyl esters of aliphatic and aromatic carboxylic acids, aliphatic ethers, cyclic ethers, and aliphatic ketones. With the donor compound as the solvent, the formula Mg _n Ti ₁ (OR) _o X _p [ED] _q (where R and X are as defined above, ED is the electron donor compound, and m is 0.5 ~56
, n is 0 or 1, p is 6 to 116, and q is 2 to 85), provided that the magnesium compound, the titanium compound, and the electron donor 1 weight of the precursor composition of the above formula obtained by recovering the precursor composition from diluted with 1 to 10 parts by weight of at least one inert carrier material and then up to 400 moles per mole of Ti of the composition, with the formula Al(R″) _c X′ _d H _e (where X′ is Cl or OR, R″ and R
are the same or different _C1 - _C14 saturated hydrocarbon groups, d is 0-1.5, e is 1 or 0, and c+d+e=3). Partial to complete activation (with the proviso that partial activation is carried out with more than 0 and less than 10 moles of said activator compound per mole of Ti of said precursor composition; and complete activation is carried out with more than 10 moles of said activator compound per mole of Ti of said precursor composition; A charge of ethylene monomer is added in a gas phase reaction zone to catalyst particles prepared by using 10 to 400 moles of said activator compound per mole of Ti, at a concentration of hydrogen per mole of said ethylene. A process comprising homopolymerizing ethylene at a temperature of 30 to 115°C by contacting in the presence of 0 to 2.0 moles. 2. The method according to claim 1, which is carried out in a fluidized bed. 3. Claim 1 in which a partially activated catalyst is fed to a reaction zone and is fully activated therein.
The method described in section. 4 The obtained granular ethylene homopolymer is
Ti content of more than 0 and less than 10ppm, more than 0
70ppm or less of one or more Cl, Br or I
Content, not more than 1 unsaturated group per 1000 carbon atoms (C
=C) The method according to claim 1. 5. The method of claim 4, wherein the granular ethylene homopolymer obtained further has a bulk density of 18 to 32 lb/ ^ft3 (288 to 513 Kg/ ^m3 ). 6. The method according to claim 5, wherein the granular ethylene homopolymer obtained further has a melt index of 0 to 50.