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 for the preparation of a particulate procatalyst composition intended for the poly ⁇ merization of olefins by reacting the carrier particles consisting of a MgCl 2 -C 2 H 5 OH-complex with TiCl 4 .
• the Ziegler- Natta-catalyst system which consists of a so-called pro ⁇ catalyst and a co-catalyst
• the procatalyst is based on a compound of a transition metal belonging to any of the groups IVA-VIII (Hubbard) of the periodical table of the elements
• the co-catalyst is based on an or- ganometallic compound of a metal belonging to any of the groups IA-III(A) (Hubbard) of the periodical table of the elements.
• the catalyst system can also comprise a carrier, on which the transition metal compound is layered, and electron donor compounds improving and modifying the cata ⁇ lytic properties.
• polyolefins In laboratory conditions polyolefins have been obtained using the procatalysts prepared in this manner. The acti- vity of the catalyst has been good. The particle size, particle size distribution and other properties of the polyolef ns have been satisfactory.
• the aim of the invention is to provide a method for the preparation of a particulate procatalyst composition inte- ded for the olefin polymerization.
• the procatalyst compo ⁇ sition should be created using a method giving a usable particle size distribution, from which the finely-divided material is essentially missing.
• the particles must be suitable for use as to their shape, chemical com ⁇ position, activity and stereospecifity.
• An aim is simul ⁇ taneously a polyolefin, the particle shape, isotacticity and crystallinity, melt viscosity and bulk density of which are suitable for use.
• the carrier and thus also the procatalyst composition contains a great deal of finely-divided ma ⁇ terial.
• the particle size distribution of the procatalyst composition then repeats in the polymerization in the particle size distribution, whereby even the polymer comp ⁇ rises a great deal of finely-divided material.
• the release of the hydrogen chloride created in the reaction between the carrier particles and the titanium tetrachloride is disricited to a molar velocity that does not exceed the threefold, preferably double, value of the molar mean velocity of the release.
• the invention is based on the idea that the reaction bet ⁇ ween the carrier particles and the TiCl 4 is maintained in such a way that a sudden discharge of the hydrogen chlori ⁇ de is prevented during the activation.
• the attenuation of the sudden discharge i.e. the distribution of the hydrogen chloride release can be carried out by any suitable chemi ⁇ cal and/or physical means.
• the prevention of sudden chemi ⁇ cal discharges is in the technical chemistry a general measure and the present invention is not related to cer- tain embodiments of this general measure only, but ex ⁇ pressly to the use of this measure to prevent the forma ⁇ tion of finely-divided material in a procatalyst.
• TiCl 4 shall preferably be added in so low a temperature that no fast reaction nor a discharge of hydrogen chloride will take place. According to one embodiment TiCl 4 is added at the temperature -30 to -10°C and preferably at the temperature -25 to -15°C.
• thermodynamic and/or physical balancing systems in the pores of the carrier particles and the TiCl 4 -solu- tion hydrogen chloride is released during a long time after the adding of the TiCl 4 .
• the release of the hydrogen chloride created in the reac- tion can also be distributed by using a strong agitation during the reaction between the carrier particles and the TiCl 4 .
• the strength of the agitation is dependent of many factors such as other means for distributing the release of the hydrogen chlorid, it can be said that the amount of agitation exceeds in this invention the conven ⁇ tional agitation values and causes an essential distribu ⁇ tion of the release of the hydrogen chloride.
• the agitation has often been accused for the breaking of the carrier parti ⁇ cles, it is very surprising that the adding of agitation will help keeping the carrier particles undamaged.
• the realization to add agitation to reach the aims of this invention must be seen against this background. Be it mentioned that in the reactor used in connection with this invention the starting speed of rotation of the mixer was raised when going over to the method according to this invention from the value 15rpm to the value 30rpm.
• a further way to distribute the release of the hydrogen chloride created in the reaction is to use an overpressure during the reaction.
• the overpressure has both a thermo ⁇ dynamic and a physical influence on the release of the hydrogen chloride.
• the thermodynamic influence is based on the prevention of the evaporation of the hydrogen chlori ⁇ de, which reflects back to the distribution reaction op- tionally creating hydrogen chloride and slowing it down.
• the physical influence is based on the fact that a higher pressure raises the gasifying temperature of the hydrogen chloride and prevents the gasification at a certain tempe ⁇ rature.
• overpressure is used during the reaction which is in the order of 1 to 100 bars, preferably about 1 to 50 bars and most preferably 1 to 5 bars.
• the release of the hydrogen chloride created in the reac ⁇ tion can also be distributed by leading to the reaction mixture or above it nitrogen gas.
• the use of an inert gas flow influences principally physically so that the hydro ⁇ gen chloride content reduced by the environment accelera ⁇ tes the removal of the hydrogen chloride created in the reaction from the pores, whereby the saturation point of the hydrogen chloride corresponding to the gasification point will never be reached. It is, however, worth while using the nitrogen or other inert gas carefully for ther- modynamically its influence is the opposite i.e. by remo ⁇ ving rapidly hydrogen chloride from the pores of the car ⁇ rier particles the possible distribution reaction creating hydrogen chloride will be accelerated and will produce abundantly of heat causing discharging of hydrogen chlori ⁇ de.
• the releasing temperature of the hydrogen chloride can be raised and its release dist ⁇ ricited according to the aim of the invention.
• the pro- ducts of the reaction between the complex and TiCl 4 such as ethoxytitanium chloride and hydrogen chloride, can also be removed by changing during the reaction the excess amount of TiCl 4 .
• the composition of the MgCl 2 -C 2 H 5 0H-complex has a decisive effect on how rapidly the hydrogen chloride created in the reaction between the complex and TiCl 4 is released.
• the preliminary results and the reaction formula (1) show that the discharge velocity increases when the C 2 H 5 OH-content increases.
• the molar ratio between the MgCl 2 and C 2 H 5 0H of the MgCl 2 -C 2 H 5 OH-complex used as the material of the car ⁇ rier particles is between 2.5 to 3.5 and preferably bet- ween about 2.7 to 3.3.
• the C 2 H 5 OH-content must be below about 60% of the weight of the procatalyst carrier material.
• carrier particles the size of which is below about 150 ⁇ m.
• the success of the invention is also influenced by the water content, mechanical strength, particle morphology and particle size distribution of the carrier particles. Therefore it has been noticed that such carrier particles consisting of MgCl 2 -C 2 H 5 0H-complex are particularly suit ⁇ able for the method according to the invention that have been prepared by a spray-crystallization method.
• Par ⁇ ticles prepared by this kind of a method are mechanically much stronger than e.g. the particles prepared by spray- evaporation and are thus particularly suitable for the method according to the invention, in which the discharge tendency of the hydrogen chloride sets high mechanical requirements for the particles. Simultaneously, particles are created giving a pore volume in the procatalyst, which is suitable for the method according to the invention.
• the release of the hydrogen chloride can also be accelera ⁇ ted by the presence of an internal donor in the reaction mixture of carrier particles and TiCl 4 . This is due to the fact that the reactions of the donor taking place in con ⁇ nection with the adding usually are exothermic. If the donor is added at a stage or in a temperature range where a discharge of the hydrogen chloride is possible, it may, in fact, lead to an uncontrolled release of the hydrogen chloride. This can happen e.g. when the reaction mixture after the adding of the TiCl 4 is heated to a temperature of about +20°C and and the donor is added to the reaction mixture.
• the above-mentioned measures for the distribution of the release of the hydrogen chloride created in the reaction can, according to the invention, be used alone or then combined in any possible way. According to one embodiment of the invention the measures are used in the manner shown in figure 5.
• B is the delay of the reaction after the adding of the donor
• C is a more rapid increase of temperature for the comple ⁇ tion of the first reaction between the carrier and the TiCl 4 ,
• D is the completion of the first reaction between the carrier and the TiCl 4
• E is the second treatment of the carrier with TiCl 4
• F is the washing
• G is the drying.
• the morphology of the carrier particles was spectacular.
• the particle size distribution was between 1.50 to 3.4 (span) and the particles did not contain finely-divided material.
• the microscope pictures of the carrier particles have been presented in connection with the microscope pictures of the procatalysts and the polymers in the handling of the results.
• the amount of the carrier was 44kg and the ratio TiCl 4 (mole)/carrier C 2 H 5 0H (mole) was 10.
• the ratio LIAV (kg)/carrier (kg) was 4.5 and the ratio TiCl 4 (mo ⁇ le)/Mg (mole) was 30.
• the agitation velocity was 15rpm.
• the second treatment with TiCl 4 was carried out by adding the reagent into a purified solid intermediary product.
• the temperature still was 110°C, the agitation velocity 15rpm and the reaction time 2 hours.
• the ratio TiCl 4 (mo- le)/Mg (mole) being also now 30.
• the product was washed four times with a hydrogen carbon solvent (LIAV) so that the ratio LIAV (kg)/carrier (kg) was 9. During the washing the agitation velocity was about the same as above. After this the product was dried with a N 2 -gas flow at the temperature 70°C without agita ⁇ tion.
• LIAV hydrogen carbon solvent
• the other treatment with TiCl 4 was carried out by adding the reagent into a purified solid intermediary product.
• the temperature still was 110°C, the agitation velocity 15rpm and the reaction time about two hours.
• the ratio TiCl 4 (mole)/Mg (mole) also now 30.
• the product was washed four times with a hydrogen carbon solvent (LIAV) so that the ratio LIAV (kg)/carrier (kg) was 9. During the washing the agitation velocity was about the same as above. After this the product was dried with a N 2 -gas flow at the temperature 70°C without agita ⁇ tion.
• LIAV hydrogen carbon solvent
• the ratio LIAV (kg)/carrier (kg) was 9.0 and the ratio TiCl 4 (mo- le)/Mg (mole) was 30.
• the temperature was raised with the mean velocity of about l°C/min. to the value 110°C, whereby the overpressu ⁇ re and the N 2 -flow were removed.
• the agitation velocity still was 15rpm.
• the temperature and the agitation were maintained in about 1 hour, after which the activation residues with the TiCl 4 excess amounts were removed by rinsing through the sieve bottom of the reactor.
• the other treatment with TiCl 4 was carried out by adding the reagent into a purified solid intermediary product.
• the ratio TiCl 4 (mole)/Mg (mole) was also now 30.
• LIAV hydro ⁇ gen carbon solvent
• procatalysts of the comparative examples and the embodiments prepared in laboratory or pilot-scale were tested under standard polymerization conditions.
• a 2-liter bench reactor was used. 20 to 30mg of procatalyst was used in each test polymerization run. To this amount 620 ⁇ ml of triethyl aluminium co-catalyst and 200 ⁇ ml of 25% heptane solution of an internal cyklohexylmethyl methoxysilane donor were added.
• intermediary medium 900ml of hep ⁇ tane was used. The polymerizations were carried out at the temperature of +70°C and in the propene monomer pressure of 10 bars.
• the partial pressure of hydrogen during the polymerization was 0.2 bars, llmmol H 2 was added to adjust the molecular weight.
• the polymerization was continued for three hours. Thereafter the activity of the procatalyst was measured on the basis of the polymerization yield.
• the solvent portion of the polymer was measured by dissolving a certain polymer amount into the solvent and measuring the evaporation residue of the pure solution.
• the bulk density and the particle size distribution of all the polymer samples were determined. In connection with the particle size distribution measurements the total amount of the finely-divided material was estimated.
• the diameter of which was smal ⁇ ler than 1mm was defined as finely-divided material.
• the isotacticity was measured by means of heptane elution and the isotacticity index was measured by using the results of the evaporation residue measurements.
• the melt index was measured at the temperature of 230°C by using a 2.16kg weight.
• the titanium content, the donor content, the particle size distribution, the catalyst yield, the catalyst activity, the polymer-isotacticity, the polymer melt index and the polymer-bulk density of the procatalysts of the embodi ⁇ ments prepared in laboratory and in pilot-scale were nor ⁇ mal for catalysts of corresponding type.
• the titanium content varied between 2.4 and 3.6% by weight in laboratory catalysts and between 2.4 and 4.5% by weight in pilot-procatalysts.
• the donor content varied between 15.9 and 19.2% by weight in laboratory-procatalysts and between 9.7 and 15.4% by weight in pilot-procatalysts (in embodiment 1 the pilot-scale donor feed was unsuccessful).
• the procatalyst yield was satisfactory varying between 74 and 99% in pilot-run and between 82 and 92% in laboratory. This shows that finely-divided material has not e.g. been rinsed off to any in any greater extent in the pilot-run compared to the laboratory-run.
• the activity of the pilot-procatalysts was at its best 15.8kgPP/g cat, which is a good value and of the same order as in the procatalysts prepared in laboratories.
• the polymer melt indices varied in laboratory procatalysts between 4.3 and 9.6 and in pilot-procatalysts between 5.0 and 7.4 (the MI of the fourth run was exceptionally 19.4) corresponding the melt index of a normal polypropene.
• pilot-scale When going over to pilot-scale a remarkable improvement can be achieved with the measures according to the inven ⁇ tion compared with the procatalysts according to the com ⁇ parative examples.
• the portion of the fine ⁇ ly-divided material of the polymer can be reduced to at least about the fourth and at the utmost to even less than a tenth of the results of the comparative tests.
• the pilot comparative example 1 where the adding order of the reagents was different (see the directions above) as much as 70% by weight was obtained as the portion of the fine ⁇ ly-divided substance, which value is much higher than those of the pilot embodiments.

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• 1991
  • 1991-11-29 FI FI915630A patent/FI92327C/fi not_active IP Right Cessation
• 1992
  • 1992-11-27 EP EP92924733A patent/EP0614466A1/en not_active Withdrawn
  • 1992-11-27 JP JP5509851A patent/JPH07501568A/ja active Pending
  • 1992-11-27 WO PCT/FI1992/000322 patent/WO1993011164A1/en not_active Application Discontinuation
• 1994
  • 1994-05-26 NO NO941970A patent/NO941970L/no unknown

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