Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond

Definitions

• the invention relates to a method of preparing a supported procatalyst of a catalyst system intended for the polymeriza ⁇ tion of olefins, in which a particulate reaction product formed from magnesium halogenide and alcohol is treated in order to remove alcohol and is activated with a transition metal compound and optionally with an electron donor.
• the so-called Ziegler-Natta catalyst system is generally used for polymerizing olefines, consisting of a so-called procata ⁇ lyst and a cocatalyst.
• the procatalyst is based on a com ⁇ pound of a transition metal of one of the groups IVB-VIII of the periodical system and the cocatalyst is based on an or- ganometallic compound of a metal of one of the groups IA- IIIA of the periodical system.
• the catalyst system usually al ⁇ so comprises electron donor compounds improving and modifying the catalytic properties.
• an inert carrier compound is usually applied to improve the po ⁇ lymerizing activity of the procatalysts , the transition metal compound being superposed on this.
• Magnesium compounds such as alkoxides, hydroxides, hydroxyhalogenides and halogenides have turned out to be important carrier compunds, the latter, : commentaryn particular magnesium chloride, having lately become the major carrier components of procatalysts.
• magnesium compounds in their basic crystalline form are not very effectively activated by a transition metal compound, their crystalline structure has to be deformed.
• This is con ⁇ ventionally done by grinding e.g. in a ball mill.
• the magnesium compound such as a magnesium chloride-like mag- nesium halogenide
• the magnesium compound is ground either as such together with an electron donor remaining in it, or even together with the final catalyst components, e.g. in a ball mill during 50-120 hours at a temperature in the range of 40-70°C.
• finely divided powder having typically a large specific surface is obtained, in which the crystal lattices of the particles are strongly deformed.
• the JP patent specification 59 215 301 discloses a method for polymerizing or copolyme- rizing ethene, in which the carrier is prepared by bringing together a hot hydrocarbonaceous emulsion of magnesium chlo ⁇ ride, ethanol and an emulsifier, and a cool liquid of the same hydrocarbon. This yields a carrier agent with spheric partic ⁇ les, in which the particle diameter varies in the range of 53-105 microns.
• the carrier is activated by suspending it at room temperature in titanium tetrachloride, after which an electron donor is further added to the mixture.
• the procata ⁇ lyst achieved by this emulsifying solidification technique is particularly appropriate for the polymerization and copolyme- rization of ethene.
• the US patent specification 4 506 027 discloses a method of preparing a procatalyst, in which firstly a solid carrier is achieved by spray drying a solution, in which the magnesium chloride is dissolved in a mixture of ethanol and methanol. The carrier containing ethanol and methanol hydroxyl thus obtained is then activated by titanium or vanadinium haloge- nides. As a result a procatalyst is obtained, which combined with an organoaluminium compound acting as a cocatalyst ser ⁇ ves well as a polymerization catalyst for alfa-olefines.
• the FI patent application 86 2459 describes the preparation of a procatalyst by spray crystallizing a mixture of magne ⁇ sium dihalogenide and alcohol into a crystalline complex com ⁇ pound whose particles, due to the lack of alcohol evaporation, have more free hydroxyl groups than in prior methods.
• the procatalyst is obtained by activating said spray crystal ⁇ lization product with a tetravalent titanium compound.
• the above chemical modification of a magnesium compound with alcohol is based on the fact that it yields a particle ⁇ like reaction product, which is e.g. a complex of magnesium halogenide and alcohol.
• the activation takes place so that the transition metal compound displaces the alcohol by reacting with it as well as is attached to the magnesium compund, whose crystal lattices are strongly deformed due to the alcohol eva ⁇ poration.
• an active procatalyst and as a by-product a reaction product of the transition metal compund and alcohol are produced.
• the compound is magnesium chloride, the alcohol is ethanol and the transition metal compound is titanium tetrachloride.
• the crystalline magnesium chloride I is first reacted with ethanol, whereby the crystalline complex II is obtained.
• the complex II is then reacted with the titanium tetrachlori ⁇ de.
• procatalyst II which comprises titanium tetrachloride on an amorphous magnesium dichloride carrier
• procatalyst residue IV which is washed out with a great surplus of titanium tetrachloride.
• the procatalyst III thus obtained has an amorphous crystal structure and a high activity in olefine polymerization. The better the catalyst residue IV is washed out, the higher is the activity obtained.
• the purpose of the present invention is to provide a method of preparing a supported procatalyst, which does not consume great amounts of raw material and does not produce hazardous waste that is harmful to the environment and difficult to handle.
• the invention also aims at a procatalyst having an applicable activity.
• the reaction product of magnesium halo ⁇ genide and alcohol is simultaneously ground and evaporated, the alcohol liberated during the grinding is removed and the structure of magnesium halogenide is formed without losing its activity by recrystallization.
• the method is most critical, since mere evaporation of alcohol does not lead to an amorphous and thus active procatalyst.
• the combined grinding and evaporating operation according to the invention can be carried out by grinding said reaction product in a heated and rapidly exchanging evaporating gas.
• any efficient mill is usable, having an adj ⁇ ustable atmospheric temperature and/or being able to receive a hot evaporating gas.
• the grinding and evaporating operation is preferably carried out in a jet mill so that one or more gaz jets carry the particles of the reaction product against each other and/or one or more counter-pieces of the jet pul ⁇ verizer with such a force and at such a temperature that they are pulverized into finely divided amorphous carriers, from which an essential portion of the alcohol has been evaporated.
• the gas used for the evaporation is inert with regard to the reaction product of magnesium halogenide and alcohol, and which stands heating to the desired evaporating temperature.
• nitrogen is a suitable gas in this respect.
• Such magnesium compounds and alcohols can be used that form an activating carrier compound when the material is being ground preferably by using a temperature gradient.
• Magnesium chloride is a preferred magnesium compund.
• Methanol and ad ⁇ vantageously ethanol can be mentioned among suitable alcohols.
• the reaction product of a magnesium compound such as magne ⁇ sium halogenide and an alcohol can be prepared by any known method. Such methods are described in the above patent specifications JP-59 215 301, US 4 506 027, FJ-86 2459 and US 4 071 674, among others. The criterion of these methods is forming a reaction product having a practicable morphology and stability.
• a preferred reaction product of magnesium halogenide and alco ⁇ hol is formed out of magnesium chloride and ethanol, ' orming together the crystalline complex MgCla x nCaHsOH, in which n is 1-6.
• the solidification of it into well' activated particles by crystallization is preferably accomplished so that the crystallizing product contains ethanol, which later, when being separated, leaves an amorphous and thus reactive carrier to be activated.
• the alcohol has a weakening effect on the crystal structure and thus also lowers the melting.point. For this reason, it is preferable to carry out the method of the pre ⁇ sent invention by applying a temperature gradient, in which the temperature of the evaporating gas is gradually raised as the alcohol is separated and removed from the reaction product formed by magnesium halogenide and alcohol.
• the al ⁇ cohol can be removed substantially totally from the reaction product formed by the alcohol and the magnesium halogenide without any recrystallization disturbing the activability of the reaction product.
• the initial and final temperatures of the temperature gradient used in the method of the invention as well as the rate of raising the temperature depend entirely on the applied reac ⁇ tion products of magnesium halogenide and alcohol, their crys ⁇ talline form and the volatility of the alcohol under the grinding conditions.
• the preferred temperature gradient of nitrogen starts at approx. 20°C and ends at approx. 270°C. This temperature is preferably raised during approx. 2-3 hours, the complex thus being ground at a temperature that is always be ⁇ low its melting point. The use of such a temperature gradient ensures the removal of substantially all the alcohol from the reaction product of magnesium halogenide and alcohol.
• a mill of this type is advantageous firstly because the carrier gas used for the grinding can also be used for evaporating the alcohol.
• the jet mill type generally known in this field can be used in the method, the general principles of which are described be ⁇ low.
• the particle-like reaction product formed of magnesium haloge ⁇ nide and alcohol is fed into the mill e.g. by priming the particle flow by gravity from a funnel and/or by using a screw conveyor.
• the mixing into the gas jet before the grin ⁇ ding chamber can be enhanced by the ejection effect.
• the jet feeding points are symmetrically placed in the walls of the vertically positioned cylindrical mill chamber.
• the jet or jets can also be fed tangentially to the wall of the mill chamber, whereby the gas flow containing particles is brought into a rotatory circulating movement which, when the chamber is vertical, can sink spirally downwards under the effect of gravity.
• the rotation of the gas* flow can be guided and/or the grinding enhanced by means of auxi ⁇ liary jets co ing from the lower part and of possible guiciing and/or counter-pieces.
• the gas jets of which there are advanta ⁇ geously at least two, are directed approximately to the cent ⁇ ral part of the cylindrical mill chamber, into which the par ⁇ ticles to be ground are also fed by priming from a funnel or by means of a conveyor screw.
• the gas flow and the ground particles are removed from behind and/or the side of the counter-piece at one or more points.
• the gas flow is generally removed from the centre of the chamber, at the upper part, and the ground par- tides from the upper and/or lower part.
• the removed particles can still be conducted into a grading equipment, in which the articles ha ⁇ ving possibly remained too coarsely grained, are screened out, not being suitable for the preparation of an active catalyst.
• a counter-piece jet mill, a material or gas accelerated jet mill, a disc or spiral jet mill and a gas accelerated jet mill can be mentioned as examples of types of jet mills suitable for the method of the present invention.
• Figures 1-4 show a schematic perspective of four jet mill models usable in the method of the present invention
• figure 5 shows a graphical drawing of the temperature gradient used in embodiment example 3 and in the comparative examples B, C and D
• figure 6 shows the evaporating equipment used in the compa ⁇ rative examples E and C
• figure 7 shows the evaporating equipment used in example D.
• the jet mill type shown in figure 1 operates with an accelerated gas flow.
• the gas feeding line is provided with a heater and/or a superheater, which is not shown in the fi ⁇ gure.
• the model shown by the figure has only one venture nozzle 1.
• the heated and accelerated gas flow 2 is conducted to a feeding device 3 of the ejector type, where the particu- late reaction product 4 of magnesium halogenide and alcohol is sucked into the gas flow. After the ejector 3 the gas and reaction product flow is made to collide with the coutnter- piece 5, whereby the reaction product is pulverized.
• the second component of the reac ⁇ tion product As a re ⁇ sult of the pulverization, the second component of the reac ⁇ tion product, the alcohol, is separated and evaporates into the accelerated and heated gas. The remaining ground solid material is removed through the opening behind the counter- piece 5 on the left in the figure.
• the reaction product formed of magnesium halogenide and alcohol as well as the gas heated to the desired evaporating temperature are accelerated in the same Venturi (laval) nozzle 6.
• the gas and the material to be ground are first mixed in a pressurized premixing unit, which is not shown in the figure. After this the gas-mass flow is conducted into a dividing unit, which divides the current into two or more essentially equally sized flows. These flows are conducted to a respective Venturi nozzle 6 shown in the figu ⁇ re. In the nozzles 6, the rate of the gas material flow even exceeds the speed of sound.
• the nozzles 6 are directed against each other so that a colliding zone is formed between the nozzles in the actual mill chamber 7.
• the nozzles are being concerned, they are mutually positioned so that the gas flows will not clog the opposite nozzle, i.e. the nozzles are not directed against each other, but in a small angle to each other. If there are three nozzles, the preferred arrangement is an 120 ° angle between the nozzles, as shown in the fi ⁇ gure.
• the gas which is heated by a heater or superheater outside the figure, is fed into the disc-shaped mill chamber 15 at two places.
• One gas flow is a so-called working gas flow 8
• the other j_s a so- called ejector gas flow 9 and the feeding can be arranged for instance by heating both or only one of the flows.
• the disc jet mill itself consists of two covers, an upper cover 10 and a lower cover 11. Between the covers there are two rings, the outer ring 12 and the inner ring 13. In the inner ring 13 through openings 14 are tangentially disposed.
• the gas flow is regulated so that there is an over-pressure in the ejector gas line 9 with regard to the working gas line 8.
• the ejector gas 9 absorbs the material fed from the ejector and feeds it further tangentially to the mill chamber 15, which is the space remaining inside the inner ring 13.
• the work gas feed 8 is fed in between the rings 12 and 13, wherefrom it is dis ⁇ charged tangentially into the mill chamber 15 through the opening 14 of the inner ring.
• the tangentially fed gas flow produces a strong rotatory movement in the gasmass flow in the mill chamber 15.
• the rotatory movement produces an annular colliding zone inside the inner ring 13 of the mill chamber 15.
• the flow formed of the gas and the mass is discharged from the disc jet mill through the hole 16 in its central part.
• Figure 5 shows the temperature gradient used in embodiment example 3 and the comparative examples b, c and d, in which the te eprature is linearly raised from 20°C to 270°O during 2,5 h.
• Such a temperature gradient is particularly suitable for the evaporating grinding of the complex MgClz x nCaHsOH.
• Figure 6 shows an ordinary three-neck flask 21 including a heating mantle 22, a thermometer 23, a magnetic mixing rod 23 and an inlet 24 and an outlet 25 for the evaporating gas (nitrogen) .
• the removed drying gas is conducted to a cold trap 26 in order to condensate and recover ethanol.
• the equipment of figure 6 is used with ⁇ out a vacuum and in the comparative example C with a vacuum suction.
• the evaporation of ethanol is to be enhanced by a fluidized bed produced by the evaporating gas.
• the equipment consists of a column 27, which is equipped with a surrounding heating mantle 28, a thermometre 29 as well as a supply 30 and removal 31 of drying gas.
• the exhaust gas is also in this case conducted to the cold trap 32 mainly in order to recover the evaporation products formed from ethanol.
• Figures 8-14 show, in respective order, the X-ray diffraction spectres of the catalysts of the embodiment examples 1-3 and the comparative examples A-D.
• the catalysts were prepared according to the following formula. 0.1 mole of the material treated with a jet mill or obtained by thermal treatment is weighed for the preparation of a catalyst. 0.1 mole of the comparative material MgClz x CsHs OH was also weighed for the catalyst synthesis. The weighing is done in an inert space, preferably a nitrogen ca ⁇ binet. The material is disposed in a c. 1 litre glass reactor in an inert space.
• the reactor is closed before being removed from the nitrogen cabinet. It is equipped with a mixer, a vertical cooler and an adjustable nitrogen feeder line.
• the catalyst After the heptane washings the catalyst is dried by means of a nitrogen gas flow.
• the catalyst yield is determined by weig ⁇ hing the recovered amount of catalyst and the titanium con ⁇ tent of the catalyst is determined.
• the indicated amounts of catalyst, aluminium alkyle and donor are added into a feed ampoule, which is connected to the reactor.
• 50 ml of heptane is additionnally added into the am ⁇ poule in order to enhance the supply.
• the feeding is done by means of a gas flow.
• hyd- rogen is ad ⁇ ded in order to provide the required hydrogen partial pressu ⁇ re.
• the polymerization itself takes place at a propylene mono ⁇ mer pressure of 10 bars and a temperature of 70°C and the duration is three hours. Then the polymer is filtered out from the medium and dried, after which the yield is determined.
• magnesium chloride is chemically activated by means of ethanol and titanium tetrachloride a stoichiometric amount of catalyst residue is obtained as a by-product of the reaction, consisting of the chlorine and ethoxide complex of titanium:
• the amount of produced catalyst residue has been observed in the examples.
• the weight of the residue (TiClaOEt) was de ⁇ termined by weighing a residue batch obtained by dry evaporat ⁇ ing the residual solution of the first titanizing reaction. Pure titanium tetrachloride was evaporated by raising the temperature and making nitrogen flow through the vessels. If a totally clean titanium tetrachloride solution is concerned, the vessels are dry evaporated already at ⁇ O'-'C. If on the contrary the solution contains titanium ethoxides, these re ⁇ main in the vessel as a solid slag. The slag amount can be determined by weighing directly in the vessel provided that the weight of the vessel is known.
• the catalyst slag obtained contains, depending on the evaporation duration and the tem ⁇ perature, 10-20% of absorbed titanium tetrachloride.
• the method of determination is not applicable to the exact measu ⁇ ring of the amount of slag material, but the method provides an adequate conception of the occurence of slag components in relation to the amount of catalyst. d.

Landscapes

• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)
• Polymerization Catalysts (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=8527912

Family Applications (1)

Country Status (5)

Families Citing this family (7)

Family Cites Families (2)

• 1989
  • 1989-02-16 FI FI890765A patent/FI83332C/fi not_active IP Right Cessation
• 1990
  • 1990-02-15 JP JP2502974A patent/JPH04504865A/ja active Pending
  • 1990-02-15 CA CA002047712A patent/CA2047712A1/en not_active Abandoned
  • 1990-02-15 EP EP90902790A patent/EP0451214A1/de not_active Ceased
  • 1990-02-15 WO PCT/FI1990/000048 patent/WO1990009402A1/en not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events