CS262452B1 - Method of 1-alkenes' polymers and copolymers production - Google Patents

Abstract

The solution relates to the production of polymers and copolymers of 1-alkenes by polymerization under pressure 0.5 to 4.0 MPa and a temperature of 50 to 150 ° C to catalytic converters at least one organic compound aluminum, at least one titanium compound and / or vanadium and at least one organic aluminum and optionally paraffinic hydrocarbon compounds to an inert oxide of elements 3b or 4b of the group of the Periodic Table of Elements. Molecular the weight of the polymer can be controlled by addition hydrogen and the catalyst can be passivated by addition paraffinic hydrocarbon with temperature melting point 25 ° C to 150 ° C.

Description

The invention relates to a process for the production of polymers and copolymers of 1-alkenes using single-phase supported catalysts based on titanium, vanadium and aluminum compounds.

Polymers and copolymers of 1-alkenes are usually prepared using transition metal catalyst systems that can be supported and are usually activated by reaction with a cocatalyst - an alkyl metal compound - directly in the polymerization apparatus. These catalysts show high polymer productivity relative to the transition metal and easily copolymerize higher 1-alkenes. Depending on the type of transition metal and ligands bound to the transition metal, both molecular weight distribution and polymerization activity can be influenced. The addition of electron donors to the catalytic system can also affect the stereoregularity of the process in propene polymerization. The source of serious technological complications is the activation of the catalyst by organometallic compounds in the polymerization reactor. This means that two components are introduced into the reactor - a catalytic precursor, usually in powder form and an organometallic solution. The free organometallic initiates the oligomerization of olefins, causing undesirable deposits on the inner walls of the polymerization apparatus. When interacting with atmospheric oxygen and moisture (eg in the event of a leak in the polymerisation equipment, during shutdown), the organometallic decomposes to aluminum oxide, which contributes to the further formation of deposits. The presence of free organometallic also negatively affects the kinetics of the polymerization, since the permanent contact of the organometallic with the active centers leads to undesirable catalyst changes, resulting in loss of activity and ultimately disadvantageous particle size distribution of the polymer, i.e. high dust content and particles below 0. , 1 mm. Post-activation transition metal catalyst systems are described, for example, in U.S. Pat. Nos. 4,302,566, 3,787,384, 4,148,754,

US 4,063,009, US 4,173,547, GB 1,484,254, GB 2,099,834, US 4,490,514A.

In recent years, single-phase transition metal catalyst systems based on transition metals 4a and 5a of the Periodic Table of Elements have been developing. In the polymerization of 1-alkenes on single-phase catalysts, there are no complications with the feeding of catalysts, no formation of deposits on the polymerization apparatus, and the obtained polymer has the desired particle morphology. Single-phase titanium and vanadium catalyst systems are described, for example, in patents

BE 884 513, BE 866 420, JA 52 000 880 and in MS. AO No. 256 961, MS. AO No. 262 451 and in MS.

AO No. 259 736.

SUMMARY OF THE INVENTION The present invention provides a process for the preparation of polymers and copolymers of 1-alkenes by polymerizing 1-alkenes of 2 to 10 carbon atoms on supported catalysts based on titanium, vanadium and aluminum compounds, wherein alkenes containing up to 20% by volume of hydrogen at 0.5-4 , 0. The MPa at 50 to 150 ° C contact the catalyst formed by the sequential anchoring of at least one organic aluminum compound, at least one titanium and / or vanadium compound and at least one organoaluminum compound to the inert oxide of elements 3b or 4b of the Periodic Table.

The present invention further provides a process for the preparation of the polymers and copolymers of 1-alkenes according to the invention, wherein the catalysts are treated with 0.5 to 100% by weight paraffinic hydrocarbon with a melting point of 25 to 150 ° C prior to polymerization.

For the catalyst useful in the production of the 1-alkene polymers and copolymers of this invention 2, a suitable carrier is silica and / or alumina having a specific surface area of 50-500 m / g, a pore volume of 0.5-3.0 ml / g, which dehydrates at at temperatures of 200 to 950 ° C with air flow and / or nitrogen in the fluidized bed for at least 4 hours. The silica thus treated contains 0.3-3.0 mmol OH groups per g depending on the dehydration temperature.

In the hydrocarbon solvent medium or in the gas phase, the support is treated with an organoaluminum component, for example, a trialkylaluminum, a dialkylhaloaluminum, a dialkylalkoxyaluminum, an alkyldihaluminum, or mixtures thereof. Reaction products are formed firmly fixed to the support surface. The molar ratio of the sum of the organometals I to the -OH groups of the support is in the range of 0.1 to 10, preferably 0.5 to 1.0. Due to the uniform application of the organometallic I, the carrier suspension or the carrier layer must be vigorously stirred. The temperature during the interaction may vary within wide limits depending on the vapor pressure of the organometallic compound at the boiling point of the hydrocarbon used, preferably at 10 to 70 ° C or at ambient temperature.

In a further stage, at least one titanium and / or vanadium compound, e.g., a halide, haloalkoxide, alkoxide, vanadium oxihalide and / or titanium II, is deposited on the anchored organoaluminum component. This reaction may preferably be carried out in a hydrocarbon medium or by direct contact of the vapors of the titanium compound and / or vanadium with the solid phase of the intermediate, preferably at room temperature. The titanium and / or vanadium compounds are firmly anchored to the support and reacted with the fixed reaction products of the previous reaction. The molar ratio of the sum of the organoaluminum compounds I to the sum of the compounds II is kept within the range of 1 to 100, preferably 5 to 20.

By chemical binding of the organometallic I to the free -OH group of the support, a modification of its reducing ability and its immobilization on the support surface is achieved. By selecting the ratio of the organometallic compound (I) to the hydroxyl groups and the ratio of the titanium and / or vanadium (II) compounds to the organoaluminum compound, active structures are formed on the surface of the support having the ability to polymerize 1-alkenes.

According to AO No. 259 736, the properties of a single-phase catalyst can be significantly improved by the use of another organometallic-organomagnesium compound. According to the present invention, a similar effect is achieved by forming an additional layer with an organoaluminum compound III, e.g., trialkyl aluminum, dialkyl aluminum halide, alkyldihaluminum, dialkylalkoxy aluminum and the like. The III / II molar ratio is maintained in the range 0.5 to 20, preferably 1 to 8. the form of the titanium and / or vanadium compounds is thus divided into two steps, which make it possible to tune the reduction, respectively more precisely, more precisely. alkylating the transition metal compound. The conditions and method of application of the organoaluminum compounds are the same as those of the previous components. The final stage of catalyst preparation is the optional drying of the solvent with an inert gas stream or evacuation.

The properties of the catalyst are further improved by the deposition of a paraffinic hydrocarbon on the surface of the catalyst particles, similarly as in U.S. Pat. AO No. 262 451. The melting point of the paraffinic hydrocarbon lies between the polymerization temperature and the maximum normal temperature of the environment in which the catalyst is produced, stored and transported. Preferably, paraffin having a melting point of 50-70 ° C, atactic polypropylene or other saturated hydrocarbons having a suitable melting point may be used. The presence of multiple bonds and heteroatoms in the paraffinic hydrocarbon chains is undesirable since they reduce the activity of the catalyst. Low molecular weight impurities of the electron donor type have the same negative effect. The paraffinic hydrocarbon can be applied to the finished catalyst suspended in a hydrocarbon solvent or simultaneously with the last catalyst component, i.e., the organoaluminum compound III. The paraffinic hydrocarbon is applied to a content of 0.5 to 50% by weight of catalyst, preferably 1 to 10% by weight. The principle of action of a paraffinic hydrocarbon is to encapsulate the catalyst particles and prevent the diffusion of impurities to the active polymerization centers during catalyst isolation, storage, transport and dosing. The formation of a diffusion barrier on the catalyst surface further stabilizes the catalyst system in the absence of monomer. The reactivity of the catalyst components decreases considerably, and a large proportion of the active centers are formed after the paraffinic hydrocarbon has melted in the reactors.

The polymerization of the 1-alkenes according to the invention on a single-phase catalyst can be carried out in a fluidized bed, in a mechanically stirred layer in the gas phase in a liquid monomer or in a solvent. It is polymerized at a temperature of 50-150 ° C; lower temperatures are preferred for higher 1-alkene polymerization with a lower softening point, higher temperatures can be used for fluidized bed polymerization of ethylene (80 to 120 ° C) and for solution polymerization of 1-alkenes in a hydrocarbon solvent (110 to 150 ° C). In the gas phase polymerization, the temperature must be kept 5-10 ° C below the melting point of the polymer to avoid agglomeration of the particles. The polymerization pressure is usually 0.5 to 4.0 MPa, the optimum is 1.8 to 2.2 MPa, because at lower monomer pressures the catalyst productivity is lower (directly proportional to the monomer pressure) and at higher pressures higher than 2.2 MPa they increase the cost of acquiring and operating pressure vessels and the compression of working media. The polymerization is preferably carried out continuously at constant pressure and temperature with continuous feed of the catalyst, monomer or mixture thereof and hydrogen and with continuous product withdrawal. The discontinuous process is not economically advantageous.

The molecular weight of the polymers can be controlled by the addition of hydrogen. Without hydrogen, ultra-high molecular weight polymers (UHMW) are formed, and as the hydrogen content increases, the polymer melt flow index decreases sharply. At a hydrogen content of 10 to 20 S by volume in the monomer mixture, strongly liquid polymer types (fiber types) are obtained.

The catalyst dosage can be controlled by the instant polymerization rate (given by the temperature of the polymer layer or solution). The catalyst can be dosed continuously (eg by an adjustable stroke pump) or batchwise, where the frequency of the individual doses can be changed. In gas phase polymerization, it is preferable to charge the powdered catalyst (the volatile content of the polymer is not increased), while in liquid phase polymerization, the catalyst / hydrocarbon slurry can be metered (no solvent drying step during catalyst preparation).

During the polymerization, spherical polymer particles are formed which are similar in shape to the parent catalyst particles and hence 1 carrier. The magnification factor is 20 to 50x, and the polymerization produces compact particles of 0.5 to 5 mm in size depending on the polymerization time (for the discontinuous process) or residence time (for the continuous process). The usual polymerization time or residence time is 1 to 8 hours, preferably 2 to 6 hours. With shorter polymerization times, the ash content of the catalytic residues in the polymer is higher, the reactor productivity is high. Conversely, longer polymerization times improve polymer quality and reduce reactor productivity. The polymer is stabilized by conventional stabilizers. Due to the high activity of the catalyst and hence the low content of catalyst residues, a small amount of stabilizers is sufficient. The catalyst is deactivated by air, water vapor and / or carbon monoxide upon exit from the reactor. Catalytic residues need not be washed.

An advantage of the process for producing polymers and copolymers of 1-alkenes according to the present invention is that an active catalyst system is used, requiring no further activation in the polymerization apparatus. By fixing the components to the carrier, their migration and undesirable side reactions leading to the disappearance of the active centers are prevented. The fixed active centers in the pores of the carrier allow the polymer to be polymerized at high speed without the formation of unwanted melted polymer slices.

This is achieved

eliminating the initial phase of a sharp rise in polymerization rate and its subsequent decrease;

constant polymerization rates for 6 to 8 h, i.e. catalyst residence times in continuous reactors;

avoiding deposits on the inner walls of the polymerization apparatus;

- high polymer bed weights ensuring high polymerization productivity;

- absence of a dust fraction in the polymer;

- high bulk density of the polymer powder (480-520 kg / m ³ );

- the ability to control polymer properties by the type of catalyst system used and the polymerization conditions.

The following examples illustrate the invention:

Examples 1 to 8

In a cleaned reactor containing 50 ml of nitrogen-stripped heptane, 2 g of silica was charged in countercurrent of pure nitrogen and the appropriate amount of organometallic (I) according to Table 1 was added. After stirring for 5 min, the vanadium and / or titanium II compound was added. 1, again stirred for 5 min, and organometallic compound III according to Table 1 was further added. The final catalyst preparation step was the removal of the solvent (nitrogen stream or evacuation).

The catalysts prepared according to Examples 1 to 8 can be obtained in the form of dry powders containing solvents up to a maximum of about 50% by weight. Above this limit, a sticky powder or slurry is obtained which cannot be successfully pneumatically conveyed and dosed into the polymer reactor. In the case of liquid phase polymerization, a catalyst / hydrocarbon slurry can be used directly.

During catalyst preparation, storage, transport and dosing, access to catalytic electron donor poisons such as oxygen, water, dienes, carbon oxides, etc. must be avoided. All operations and handling of the catalyst must be carried out in an inert atmosphere such as a pure nitrogen stream. or argon.

Table 1

Example Content of -OH group- Organometallic I Compound Ti, V Organometallic III pin mmol / g support II mmol / g support mmol / g support mmol / g

1 0.55 AlEt ₃ (0.30) TiCl ₄ (0.1) Al (OEt) Et- (0,15) .2 0.55 AlEt ₂ Cl (5.5) TiCl ₄ (0.01) AlEt ₃ (0.9) HC ₄ (0,05) AliBu ₃ 3) 3 0.75 AlEt ₃ (0.25) Ti (OEt) ₄ (0.1) Al (OBu) Bu ₂ (0.2) AlEt ₂ Cl (0.25) AlEt ₂ Cl (0 , D 4 0.75 AlEtj (0.25) AlEt ₂ Cl (0.25) TiBuClj (0.1) AliBUj 15) 5 0.75 AlEt ₂ Cl (0.08) VOC1 ₃ (0.1) AlEt ₃ (0.2) HC ₄ (0,05) 6 0.80 AlEt ₂ (0,3) AlEt ₂ (0,3) TiCl ₄ (0.1) Al (OEt) Et ₂ (0.2) 7 2.80 Al (OEt) ET ₂ 7) Ti (OEt) ₄ (2.7) AliBu ₃ 3) 8 2.80 AlHex ₃ (1.03) TiCljEt (1.03) AliBUj 1) Comment 1. Abbreviations i : Et = ethyl OEt = ethoxide Bu = n-butyl OBU = n-butoxide Hex = hexyl iBu = isobutyl 2. A carrier was used Silica DAVISON 952 specific surface area 250 up to 300 m ^ / g, about volume

pore of 1.6 ml / g with a maximum pore radius of 11 nm, activated at 800 ° C (Examples 1 and 2),

600 ° C (examples 3-5) and 200 ° C (examples 7 and 8) and alumina having a specific surface area of 150 m ^ / g, a pore volume of 1.0 ml / g, a maximum pore radius of 40 nm, dried at 800 ° C (Example 6).

The polymerizations were carried out according to the following examples (molar ratios of monomer mixture composition and polymer properties - see Table 2):

Example 9

The powder catalyst was fed to the bottom of a continuous pilot plant reactor by means of a nitrogen overpressure metering device. The polymerization takes place in a fluidized bed consisting of a blend of powdered polymer and a catalyst maintained in fluid flow by the monomer mixture. The flow rate of the mixture is 3 to 6 times higher than the minimum speed required for fluidization. A steady state is defined, defined by a pressure of 1.8 to 2.0 MPa and a temperature in the range of 70 to 110 ° C. A polymer is formed which, depending on the rate of formation, is discharged discontinuously from the reactor. Reactor productivity depends on residence time (typically 2 to 6 hours), cooling efficiency of the recycled monomer mixture (given by design parameters), and catalyst activity and concentration (max. Productivity 20 kg / h).

Example 10

A laboratory reactor of 1.5 dm, allowing the preparation of 300 g of polymer, was purged at 500 ml / min of ultra-nitrogen nitrogen for 16 hours, then pressurized 10 times with nitrogen to 0.6 MPa at polymerization temperature and finally purged with ethylene 2 times. The reactor temperature was maintained at the desired polymerization temperature by reactor jacket tempering. A mixture of monomers (or hydrogen) was charged into the reactor. The polymerization was initiated by breaking the glass flask with 50-150 mg of catalyst. The fluidized bed was kept buoyant by mechanical stirring using a two-way spiral, the rate of polymerization was measured from the consumption of the replenished monomer mixture. After about 4 hours, the reactor was depressurized, opened and the polymer further processed (stabilization, etc.).

Example 11

In a 1.5 dm ³ laboratory reactor, the solvent (n-hexane, n-heptane, 1-hexene or 1-decene) was stripped off with a stream of ultra-pure nitrogen to evaporate more than 15% by weight of the solvent. Thereafter, the reactor pressure was adjusted by feeding the monomer mixture at the polymerization temperature, which was initiated by breaking the glass vial with catalyst for 4 h. After opening the reactor, the polymer was isolated by evaporating the solvent and drying in an oven.

After deactivation of the catalyst (eg by air), the polymers must be stabilized against UV radiation and oxidation at higher temperatures by conventional stabilizers. For example, a mixture of sterically hindered phenolic antioxidant and tri (nonylphenyl) phosphate in a weight ratio of 1: 0.5 to 1.5 in an amount of 0.01 to 0.03% by weight per polymer can be used. Due to the high activity of the catalyst, the amount of stabilizer required is low. The polymer consists mainly of large particles (usually 0.5 mm and larger) and therefore does not need to be granulated before processing.

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Claims (2)

object of the invention A process for the preparation of polymers and copolymers of 1-alkene by 2 to 10 carbon atoms of 1-alkene on supported catalysts based on titanium, vanadium and aluminum compounds, characterized in that the 1-alkenes containing up to 20% by volume of hydrogen at a pressure of 0.5 up to 4.0 MPa and at a temperature of 50 to 150 ° C contact the catalyst transportable by successively anchoring at least one organic aluminum compound, at least one titanium compound and / or vanadium and at least one organic aluminum compound to the inert oxide of Group 3b or 4b elements of elements. 2. A process for the preparation of polymers and copolymers of 1-alkenes by polymerizing 1-alkenes of 2 to 10 carbon atoms on supported catalysts according to claim 1, characterized in that the catalysts are treated with 0.5 to 100% by weight paraffinic hydrocarbon of melting point 25 to 100. 150 [deg.] C.