RU2753875C1 - Catalytic system, method for its preparation and method for producing reactor powder of ultra-high molecular weight polyethylene - Google Patents

Abstract

FIELD: ultra-high molecular weight polyethylene production.

SUBSTANCE: invention relates to the field of obtaining ultra-high molecular weight polyethylene UHMWPE, which has a special morphology and nanostructure, namely, to a catalytic system for obtaining a reactor powder of ultra-high molecular weight polyethylene by polymerization of ethylene based on complexes bis[2-[R¹]-4-[R²]-6-[(R³-imino)methyl]-phenoxy]titanium (IV) dichloride containing substituents R¹, R² and R³ in the following combinations: R¹ is 1-(4-tert-butylphenyl)ethyl or 1-phenylethyl, R² is a hydrogen atom, R² is pentafluorophenyl, R² is 1-phenylethyl, R² is methyl, R³ is pentafluorophenyl, R¹ is isobornyl, R² is a hydrogen atom, R³ - pentafluorophenyl, R¹ - cumyl, R² - hydrogen atom or methyl, R³ - 4-allyloxyphenyl, R¹ - tert-butyl, R² - methoxy, R³ - 4-allyloxyphenyl, and an organometallic activator consisting of a mixture of diethylaluminum chloride and di-n-butylmagnesium, which provides a reactor powder of ultra-high molecular weight polyethylene suitable for solution-free solid-phase processing into ultra-high modulus ultra-high-strength fibers and threads in an environment of aliphatic or aromatic solvents. The invention also relates to a method for preparing a catalytic system and to a method for catalytic polymerization of ethylene to obtain an ultra-high molecular weight polyethylene reactor powder.

EFFECT: increasing the activity of the catalytic system, which does not contain methylalumoxane as an activator, for the synthesis of UHMWPE and in obtaining by the claimed method using the proposed catalytic system of ultra-high molecular weight polyethylene suitable for processing by a solutionless solid-phase method.

7 cl, 1 tbl, 17 ex

Description

The invention relates to the field of producing ultra-high-molecular-weight polyethylene (UHMWPE), which has a special morphology and nanostructure, which ensures its processing into ultra-strong and high-modulus fibers and ribbons by a solutionless solid-phase method. These structural materials retain their physical and mechanical properties under extreme operating conditions and are used for the manufacture of ropes, nets, body armor, helmets and aircraft components.

It is known that the widely used technologies for the synthesis of UHMWPE by polymerizing ethylene using polycentre Ziegler-Natta catalytic systems do not allow the production of reactor powders (RP), which are processed into fibers using simplified methods, eliminating the need to use expensive organic solvents [RU 2552636, С08F 4/642, C08F 110/02, 10.06.2015]. RP UHMWPE, processed by a solutionless solid-phase method, which consists in successive processes of compacting, monolithization and orientational drawing, have a number of specific characteristics. Among them, one of the most important is the bulk density of the RP, which correlates with the pore volume and particle morphology. The criticality of this indicator of the polymer, which determines the possibility of achieving high mechanical properties of the resulting material, is demonstrated, for example, in [Aulov VA and others. Features of compacting reactor powders of ultra-high molecular weight polyethylene // High-molecular compounds. Ser. A. - 2000. - T. 42. - No. 11. - S. 1843-1850]. As a result of testing several dozen different samples of UHMWPE, the authors developed a criterion for the selection of polymers that can be processed into high-strength threads. It is shown that UHMWPE RPs with a bulk density of less than 0.150 g / cm ³ undergo effective compaction and monolithization.

Promising catalytic systems for obtaining RP of UHMWPE suitable for solid-phase processing are monocenter systems of the post-metallocene type based on phenoxyimine titanium complexes. The key advantage of such systems is the ability to “fine-tune” the catalytic properties by varying the ligand environment of the central atom and the polymerization conditions.

Patent [RU 2459835, C08F 4/642, C07F 7/28, 27.08.2012] describes a catalytic system based on bis (phenoxyimine) titanium chloride complexes functionalized with oxyallyl groups and activated with methylalumoxane (MAO). This catalytic system has an activity of 164-555 kg _PE / (g _Ti × MPa × h). UHMWPE RPs obtained by the method of suspension polymerization of ethylene in toluene have a molecular weight of M _η = (1.7-7.0) × 10 ⁶ g / mol, a bulk density of 0.030-0.127 cm ³ / g, and can be processed by cold molding into high modulus (over 80 GPa) and ultra-high strength (over 2 GPa) products.

In the patent [RU 2561921, С08F 10/02, С08F 2/06, 10.09.2015] it is shown that the catalytic activity of the system based on functionalized oxyallyl groups of bisphenoxyimine complexes of titanium chloride, activated with MAO in the medium of aliphatic solvents, is 310-530 kg _PE / (g _Ti × MPa × h). Varying used titanium complex compound and the polymerization conditions allows to obtain UHMWPE RP (M _η = (3.1-4.9) × 10 ⁶ g / mol and a bulk density of 0.044-0.083 cm ³ / g), improved morphology, processed in sverhvysokomodulnye (more than 130 GPa) and ultra-high-strength (over 2 GPa) tapes and fibers by solvent-free spinning.

Known catalytic system based on MAO-activated bisphenoxyimine complexes of titanium chloride containing perfluorophenyl fragments [RU 2624215, С08F 110/02, С08F 4/642, 03.07.2017]. The described catalytic system demonstrates an activity of 170-230 kg _PE / (g _Ti × MPa × h) in the polymerization of ethylene in hexane, heptane, or gasoline and leads to the production of ultra-high molecular weight polyethylenes (M _η = (4.6-6.0) × 10 ⁶ g / mol , bulk density 0.045-0.089 cm ³ / g). UHMWPE RPs have an improved morphology, which ensures the achievement of superstrong (over 2.7 GPa) and ultrahigh modulus (over 110 GPa) properties of ribbons or fibers obtained by the solid-phase method.

The closest to the proposed catalytic system (prototype) is described in the patent [RU 2552636, C08F 4/642, C08F 110/02, 10.06.2015] a system based on substituted bis (phenoxyimine) titanium halide complexes containing perfluorophenyl fragments. Depending on the conditions of ethylene polymerization and the nature of the titanium (IV) complex, the reduced catalytic system upon activation with MAO in a toluene medium has an activity of 122-1880 kg _PE / (g _Ti × MPa × h). This patent shows the possibility of obtaining reactor UHMWPE powders (M _η = (3.1-6.0) × 10 ⁶ g / mol, bulk density 0.055-0.100 cm ³ / g), capable of processing into extra strong fibers and ribbons (modulus of elasticity up to 3.5 GPa, breaking strength up to 150 GPa) by cold solid-phase forming.

The main common disadvantage of the catalytic systems listed above is the need to use methylalumoxane as an activator. MAO is prone to oligomerization, and its solutions are unstable during storage. This causes significant differences both in the properties of catalysts generated from different MAO samples under the same conditions and in the properties of the resulting polymers. The high cost of MAO determines the high cost of the entire catalytic process and the resulting polymer, which significantly limits the applicability of these catalytic systems.

The objectives of the present invention are the creation of a new effective catalytic system for the synthesis of UHMWPE, which does not contain MAO as an activator, and the development of a method for producing UHMWPE using the proposed catalytic system.

The technical result is a high activity of the catalytic system, which does not contain methylalumoxane as an activator, for the synthesis of UHMWPE and ultra-high molecular weight polyethylene obtained by the claimed method using the proposed catalytic system, suitable for processing by a solutionless solid-phase method.

The tasks are solved by creating a new catalytic system based on complexes of titanium (IV) dichloride and a combined organometallic activator, consisting of a mixture of aluminum and organomagnesium compounds, and developing a method for producing UHMWPE using this catalytic system. The catalytic system is characterized by the fact that the titanium (IV) dichloride complex has a general structure

,

,

those. is bis [2- [R¹] -4- [R²] -6 - [(R³-imino) methyl] phenoxy] titanium (IV) dichloride, in whichssubstituent R¹ selected from the group consisting of primary, secondary or tertiary alkyls, mono- or diaryl-substituted secondary alkyls, mono-, di- or triaryl-substituted tertiary alkyls, cyclo- or bicycloalkyls; Deputy R² regardless of the substituent R¹is selected from the group consisting of a hydrogen atom H, alkyls or alkoxyls of any structure; the substituent R₃from group including alkyl-substituted or alkyl-, alkenyl- or alkynyloxy-substituted non-fluorinated or polyfluorinated mono- or multinuclear aryls (phenyl, biphenyl, naphthyl or any other aryl not containing heteroatoms).

Preferred combinations of substituents R ¹ , R ² and R ³ include the following combinations: R ¹ = 1- (4-tert-butylphenyl) ethyl, R ² = H, R ³ = pentafluorophenyl; R ¹ = 1- (phenyl) ethyl, R ² = H, R ³ = pentafluorophenyl; R ¹ = 1- (phenyl) ethyl, R ² = methyl, R ³ = pentafluorophenyl; R ¹ = isobornyl, R ² = H, R ³ = pentafluorophenyl; R ¹ = cumyl, R ² = H, R ³ = 4-allyloxyphenyl; R ¹ = cumyl, R ² = methyl, R ³ = 4-allyloxyphenyl; R ¹ = tert-butyl, R ² = methoxy, R ³ = 4-allyloxyphenyl.

The organoaluminum component of the activator is trimethylaluminum (TMA), triethylaluminum (TEA), triisobutylaluminum (TIBA), tri-n-butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, dimethylaluminum chloride (DMAE), diethylaluminum chloride (DMAE) , diisobutylaluminum chloride, methylaluminum sesquichloride, ethylaluminum sesquichloride and other similar compounds or mixtures thereof in any combination, preferably DEAC. As the organomagnesium component of the activator, an organomagnesium compound with one (alkylmagnesium halide) or two (dialkylmagnesium) alkyl fragments containing from 1 to 5 carbon atoms is used, preferably di-n-butylmagnesium.

The problem is also solved by a method for producing a catalytic system, in accordance with which the following steps are carried out sequentially in one reactor with stirring: a) a solution of the organoaluminum component is prepared in an aliphatic or aromatic solvent in an inert gas atmosphere; b) add to this solution the organomagnesium component of the activator; c) add to the mixture obtained one of the above complex compounds - bis [2- [R ¹ ] -4- [R ² ] -6 - [(R ³ -imino) methyl] phenoxy] titanium (IV) dichloride. The solvent used is aliphatic (n-hexane, n-heptane , n-octane, n-nonane or mixtures thereof in any ratio) or aromatic (benzene, toluene, o-xylene, m-xylene, p-xylene or their mixtures in any ratio) compounds. The result is the catalyst system described above.

In accordance with the present invention, there is provided a method for producing a reactor powder of ultra-high molecular weight polyethylene by catalytic polymerization using the proposed catalytic system. Ethylene polymerization is carried out under the following conditions: temperature in the range of 20-60 ° С, constant pressure of ethylene in the range from 0.05 to 0.5 MPa, concentration of titanium complex 10^-4-ten^-6 mol / L, molar ratio of components Ti: Al: Mg = 1: (250-1000) :( 10-100). Synthesis of complex compounds bis [2- [R¹] -4- [R²] -6 - [(R³-imino) methyl] phenoxy] titanium (IV) dichlorides carried out according to the methods described in [RU 2552636, С08F 4/642, С08F 110/02, 06/10/2015] and [RU 2561921, С08F 10/02, С08F 2/06, 09/10/2015]. The solvent is selected from aliphatic (n-hexane, n-heptane, n-octane, n-nonane or mixtures thereof in any ratio) or aromatic (benzene, toluene, o-xylene, m-xylene, p-xylene or mixtures thereof in any ratio) compounds.

Achievement of the technical result is confirmed by the following examples, which do not limit the scope of this invention.

Example 1.

The preparation of the catalytic system is carried out in a 300 ml stainless steel reactor. The reactor is preliminarily evacuated for 1-2 h at 85 ° C, then the reactor is filled with argon and cooled to an experiment temperature of 35 ° C. With stirring in a countercurrent of argon, 80.0 ml of toluene, 191.09 mg of diethylaluminum chloride (1.585 mmol), 23.27 mg of di-n-butylmagnesium (0.168 mmol) and 2.43 mg (2.402 × 10 ^-3 mmol) bis [2- [R ¹ ] -4- [R ² ] -6 - [(R ³ -imino) methyl] phenoxy] titanium (IV) dichloride, where R ¹ = 4-tert-butylphenylethyl, R ² = H, R ³ = pentafluorophenyl. Then, without switching off the stirring, the argon is vented, ethylene is fed to the test pressure of 0.10 MPa. The polymerization reaction is stopped after 1.0 h by adding isopropyl alcohol (15 ml) to the reactor. The polymer is filtered off on a Buchner funnel and dried in air to constant weight.

The PE yield is 6.76 g, the bulk density is ρ = 0.057 g / cm ³ . The molecular weight M _η , measured by viscometry according to ASTM D-4020, is 6.1 × 10 ⁶ g / mol. The activity of the catalytic system is 588 kg _PE / (g _Ti × MPa × h).

Examples 2-16, in which the combinations of substituents R are varied¹, R²and R³, the concentration of bis [2- [R¹] -4- [R²] -6 - [(R³-imino) methyl] phenoxy] titanium (IV) dichloride, molar ratio of components Ti: Al: Mg, solvent, polymerization temperature and ethylene pressure are similar to example 1 under the conditions shown in the Table.

Example 17.

The reactor UHMWPE powder obtained in example 1 is compacted, monolithized and subjected to uniaxial orientational drawing similarly to the method described in the patent [RU 2552636, С08F 4/642, С08F 110/02, 10.06.2015]. The measured, averaged over 6 samples, the values of the modulus of elasticity (E), breaking strength σ and breaking elongation ε are, respectively: Е = 140 GPa, σ = 2.80 GPa, ε = 2.3%.

table

No. Titanium complex compound Conditions Output, g Activity,
kg _PE /
(g _Ti × MPa × h) M _η × 10 ^-6 ,
g / mol Bulk
density,
g / cm ³ R ¹ R ² R ³ C _Ti ,
mol / L Attitude
Ti: Al: Mg Solvent T, ° С P, MPa 1 1- (4-tert-butyl-
phenyl) ethyl H pentafluorophenyl 3 × 10 ^-5 1: 660: 70 toluene 35 0.10 6.76 588 6.1 0.057 2 1- (4-tert-butyl-
phenyl) ethyl H pentafluorophenyl 1 × 10 ^-5 1: 440: 60 toluene + benzene 40 0.45 7.92 460 5.2 0.053 3 1- (4-tert-butyl-
phenyl) ethyl H pentafluorophenyl 1 × 10 ^-4 1: 1000: 55 toluene +
m-xylene twenty 0.05 8.58 448 5.9 0.051 4 1- (4-tert-butyl-
phenyl) ethyl H pentafluorophenyl 1 × 10 ^-6 1: 250: 30 n-heptane 60 0.50 0.95 496 2.6 0.058 5 1-phenylethyl H pentafluorophenyl 2 × 10 ^-5 1: 550: 15 toluene +
p-xylene 35 0.15 6.23 542 4.7 0.062 6 1-phenylethyl H pentafluorophenyl 6 × 10 ^-6 1: 650: 45 n-heptane +
n-hexane 55 0.45 2.59 250 3.3 0.061 7 1-phenylethyl methyl pentafluorophenyl 1 × 10 ^-5 1: 450: 25 toluene +
o-xylene thirty 0.30 4.44 386 5.1 0.059 eight 1-phenylethyl methyl pentafluorophenyl 7 × 10 ^-6 1: 680: 35 n-heptane +
n-octane 60 0.50 2.28 170 1.8 0.066 nine disfigured H pentafluorophenyl 3 × 10 ^-5 1: 880: 100 toluene 25 0.25 5.12 178 3.7 0.064 ten disfigured H pentafluorophenyl 2 × 10 ^-5 1: 780: 45 n-heptane +
n-hexane 50 0.40 3.16 103 2.7 0.067 eleven cumil methyl 4-allyloxyphenyl 1 × 10 ^-5 1: 850: 55 toluene + benzene thirty 0.30 3.41 297 3.9 0.069 12 cumil methyl 4-allyloxyphenyl 1 × 10 ^-5 1: 300: 15 n-heptane +
n-nonan 60 0.35 2.11 138 2.5 0.081 13 cumil H 4-allyloxyphenyl 2 × 10 ^-5 1: 550: 45 toluene thirty 0.15 4.87 442 4.4 0.072 fourteen cumil H 4-allyloxyphenyl 1 × 10 ^-5 1: 400: 10 n-heptane +
n-hexane 45 0.35 2.82 210 1.9 0.063 15 tert-butyl methoxy 4-allyloxyphenyl 4 × 10 ^-5 1: 500: 35 toluene + benzene 50 0.10 6.05 395 4.1 0.073 16 tert-butyl methoxy 4-allyloxyphenyl 5 × 10 ^-6 1: 450: 20 n-heptane 55 0.50 2.07 216 2.8 0.077

Claims (21)

1. Catalytic system for producing reactor powder of ultra-high molecular weight polyethylene by polymerizing ethylene based on complexes of bis [2- [R ¹ ] -4- [R ² ] -6 - [(R ³ -imino) methyl] -phenoxy] titanium (IV) dichloride overall structure

, containing substituents R¹, R² and R³ in the following combinations: R ¹ is 1- (4-tert-butylphenyl) ethyl or 1-phenylethyl, R ² is a hydrogen atom, R ³ is pentafluorophenyl, R ¹ is 1-phenylethyl, R ² is methyl, R ³ is pentafluorophenyl, R ¹ is isobornyl, R ² is a hydrogen atom, R ³ is pentafluorophenyl, R ¹ is cumyl, R ² is a hydrogen atom or methyl, R ³ is 4-allyloxyphenyl, R ¹ is tert-butyl, R ² is methoxy, R ³ is 4-allyloxyphenyl, and an organometallic activator consisting of a mixture of diethylaluminum chloride and di-n-butylmagnesium, providing a reactor powder of ultra-high-molecular-weight polyethylene, suitable for solution-free solid-phase processing into ultra-high-modulus ultra-high-strength fibers and threads, in an environment of aliphatic or aromatic solvents. 2. A method of preparing a catalytic system according to claim 1 for obtaining a reactor powder of ultra-high molecular weight polyethylene by ethylene polymerization, characterized in that the following stages are carried out in sequence in one reactor with stirring: a) preparing a solution of diethylaluminum chloride in an aliphatic or aromatic solvent in an inert gas atmosphere; b) adding di-n-butyl magnesium to the resulting solution; c) adding to the resulting mixture of one of the complex compounds of titanium bis [2- [R¹] -4- [R²] -6 - [(R³-imino) methyl] -phenoxy] titanium (IV) dichloride, which contains substituents R¹, R² and R³ in the following combinations: R ¹ is 1- (4-tert-butylphenyl) ethyl or 1-phenylethyl, R ² is a hydrogen atom, R ³ is pentafluorophenyl, R ¹ is 1-phenylethyl, R ² is methyl, R ³ is pentafluorophenyl, R ¹ is isobornyl, R ² is a hydrogen atom, R ³ is pentafluorophenyl, R ¹ is cumyl, R ² is a hydrogen atom or methyl, R ³ is 4-allyloxyphenyl, R ¹ is tert-butyl, R ² is methoxy, R ³ is 4-allyloxyphenyl. 3. The method according to claim 2, characterized in that the solvent used is individual aliphatic compounds, for example, n-hexane, n-heptane, n-octane, n-nonane or mixtures thereof in any ratio, or individual aromatic compounds, for example , benzene, toluene, o-xylene, m-xylene, p-xylene or mixtures thereof in any ratio. 4. A method of catalytic polymerization of ethylene to obtain a reactor powder of ultra-high molecular weight polyethylene suitable for processing by a solutionless solid-phase method, characterized in that the catalyst system is used as a catalyst according to claim 1 or prepared according to claims. 2, 3. 5. The method according to claim 4, characterized in that the ethylene polymerization process is carried out at a constant temperature of 20-60 ° C and at a constant ethylene pressure of 0.05-0.5 MPa. 6. The method according to claim 4, characterized in that the concentration of the complex of bis [2- [R ¹ ] -4- [R ² ] -6 - [(R ³ -imino) methyl] -phenoxy] titanium (IV) dichloride is 10 ^-4 -10 ^-6 mol / l, while the molar ratio of the components Ti: Al: Mg is 1: 250-1000: 10-100. 7. The method according to claim 4, characterized in that individual aliphatic compounds are used as a solvent, for example, n-hexane, n-heptane, n-octane, n-nonane or mixtures thereof in any ratio, or individual aromatic compounds, for example , benzene, toluene, o-xylene, m-xylene, p-xylene or mixtures thereof in any ratio.