Preparation method and application of a ziegler-natta catalyst for efficiently preparing low-entanglement polyethylene

Abstract

The invention relates to a preparation method of a Ziegler-Natta catalyst for efficiently preparing low entanglement polyethylene and an application. The preparation method comprises the following steps that a prepared alcohol absorbing porous carrier and a prepared polyhedral oligomeric silsesquioxane molecule / Mg mixture are stirred in tetrahydrofuran and filtered, solid powder is dried until the solid powder flows freely, and a carrier used for preparing the low entanglement polyethylene catalyst is obtained; then, a carrier of an aluminium alkyl modified catalyst is prepared through the aluminium alkyl; and finally, a TiC14 tetrahydrofuran solution is added into the carrier of the aluminium alkyl modified catalyst, after stirring, the solid powder is washed by means of the tetrahydrofuran solution and dried until the solid powder flows freely, and the Ziegler-Natta catalyst for efficiently preparing the low entanglement polyethylene is obtained. POSS can be assembled into a microsphere with particle diameter being 20-100 nm in a pore passage of the porous carrier. The active points are divided effectively. The intervals between active centers are increased. The occurrence of chain overlapping in the polymerization process is restrained. The low entanglement polyethylene Ziegler-Natta can be prepared efficiently with the polymerizing temperature being higher than or equal to 60 DEG C.

Description

technical field

[0001] The invention relates to the technical field of olefin polymerization reaction catalysts, in particular to a method for preparing a Ziegler-Natta catalyst for efficiently preparing low-entanglement polyethylene and a preparation method for low-entanglement polyethylene. Background technique

[0002] The polyethylene chain entanglement structure is a very important condensed state structure, which largely determines the melt viscoelasticity, chain segment dynamics, processing and other properties of polymers, and also determines the microscopic morphology of polyethylene after processing. and performance. In 1 mg of commercial UHMPWE primary particles with a molecular weight of 1 million, the content of entanglement points can reach 10 14 indivual. A large number of chain entanglements make the material melt viscous and extremely difficult to process. After UHMWPE is formed into fibers, a large number of chain entanglements will also cause uneven fib...

Examples

Embodiment 1

[0033] (1). 1.0g porous carrier SiO with a pore diameter of 20nm 2 After mixing with 6mmol of 1,4-butanediol in 20mL of tetrahydrofuran (THF) solution for 4h, the alcohol-modified porous support was obtained, and the alcohol-modified porous support was washed with 20mL of THF for 5 times to obtain 1,4-butanediol A porous carrier for alcohol adsorption; (2). The organic substituents of polyhedral oligomeric silsesquioxane (POSS) molecules are replaced with methyl and hydroxyl groups, wherein one POSS molecule contains two hydroxyl groups to obtain a modified The polyhedral oligomeric silsesquioxane molecule of the POSS molecular diameter is 1nm; (3). The modified polyhedral oligomeric silsesquioxane molecule in step (2) is mixed with 6mmolMgCl 2 (The molar ratio of 1,4-butanediol to magnesium atoms is 1) according to the molar ratio of hydroxyl moles in POSS to Mg atoms is 4%, mixed in 20mLTHF to prepare polyhedral oligomeric silsesquioxane molecules / Mg Mixture; (4). The polyh...

Embodiment 2

[0036] (1). After mixing 1.0g of porous carrier alumina with a pore diameter of 100nm and 6mmol of 1-butanol in 20mL of tetrahydrofuran (THF) solution for 4h, an alcohol-modified porous carrier was obtained, which was washed with 20mL of THF to obtain an alcohol-modified Porous carrier 1 time to obtain a porous carrier adsorbed by 1-butanol; (2). The organic substituents of polyhedral oligomerization silsesquioxane (POSS) molecules are replaced with tert-butyl and hydroxyl groups, wherein one POSS molecule Containing 3 hydroxyl groups on the surface, obtain modified polyhedral oligomerization silsesquioxane molecule, POSS molecular diameter is 10nm; (3). The polyhedral oligomerization silsesquioxane modified in step (2) Molecule and 0.6mmol ethoxymagnesium (1-butanol to magnesium molar ratio is 10) are mixed in 20mLTHF according to the molar ratio of hydroxyl moles and Mg atoms in POSS to prepare polyhedral oligomeric silsesquioxane / Mg mixture; (4). The mixture of polyhedral ...

Embodiment 3

[0039] (1). After mixing 1.0 g of porous carrier titanium dioxide with a pore diameter of 1 μm and 6 mmol of ethanol in 20 mL of tetrahydrofuran (THF) solution for 6 hours, an alcohol-modified porous carrier was obtained, and washed with 20 mL of THF to obtain an alcohol-modified porous carrier for 5 times , to obtain a porous carrier adsorbed by ethanol; (2). The organic substituents of polyhedral oligomerization silsesquioxane (POSS) molecules are substituted with isopropyl and hydroxyl groups, wherein one POSS molecule contains one hydroxyl group , to obtain modified polyhedral oligomerized silsesquioxane molecules, POSS molecular diameter is 20nm; (3). The modified polyhedral oligomerized silsesquioxane molecules in step (2) are mixed with 3mmol magnesium hydroxide ( Ethanol and magnesium molar ratio are 2) according to the mol ratio of hydroxyl molar number and Mg atom in POSS, be 10%, mix in 20mLTHF, prepare polyhedral oligomeric silsesquioxane / Mg mixture; (4). Step (3) ...

technical field

[0001] The invention relates to the technical field of olefin polymerization reaction catalysts, in particular to a method for preparing a Ziegler-Natta catalyst for efficiently preparing low-entanglement polyethylene and a preparation method for low-entanglement polyethylene. Background technique

[0002] The polyethylene chain entanglement structure is a very important condensed state structure, which largely determines the melt viscoelasticity, chain segment dynamics, processing and other properties of polymers, and also determines the microscopic morphology of polyethylene after processing. and performance. In 1 mg of commercial UHMPWE primary particles with a molecular weight of 1 million, the content of entanglement points can reach 10 14 indivual. A large number of chain entanglements make the material melt viscous and extremely difficult to process. After UHMWPE is formed into fibers, a large number of chain entanglements will also cause uneven fib...

Examples

Embodiment 1

[0033] (1). 1.0g porous carrier SiO with a pore diameter of 20nm 2 After mixing with 6mmol of 1,4-butanediol in 20mL of tetrahydrofuran (THF) solution for 4h, the alcohol-modified porous support was obtained, and the alcohol-modified porous support was washed with 20mL of THF for 5 times to obtain 1,4-butanediol A porous carrier for alcohol adsorption; (2). The organic substituents of polyhedral oligomeric silsesquioxane (POSS) molecules are replaced with methyl and hydroxyl groups, wherein one POSS molecule contains two hydroxyl groups to obtain a modified The polyhedral oligomeric silsesquioxane molecule of the POSS molecular diameter is 1nm; (3). The modified polyhedral oligomeric silsesquioxane molecule in step (2) is mixed with 6mmolMgCl 2 (The molar ratio of 1,4-butanediol to magnesium atoms is 1) according to the molar ratio of hydroxyl moles in POSS to Mg atoms is 4%, mixed in 20mLTHF to prepare polyhedral oligomeric silsesquioxane molecules / Mg Mixture; (4). The polyh...

Embodiment 2

[0036] (1). After mixing 1.0g of porous carrier alumina with a pore diameter of 100nm and 6mmol of 1-butanol in 20mL of tetrahydrofuran (THF) solution for 4h, an alcohol-modified porous carrier was obtained, which was washed with 20mL of THF to obtain an alcohol-modified Porous carrier 1 time to obtain a porous carrier adsorbed by 1-butanol; (2). The organic substituents of polyhedral oligomerization silsesquioxane (POSS) molecules are replaced with tert-butyl and hydroxyl groups, wherein one POSS molecule Containing 3 hydroxyl groups on the surface, obtain modified polyhedral oligomerization silsesquioxane molecule, POSS molecular diameter is 10nm; (3). The polyhedral oligomerization silsesquioxane modified in step (2) Molecule and 0.6mmol ethoxymagnesium (1-butanol to magnesium molar ratio is 10) are mixed in 20mLTHF according to the molar ratio of hydroxyl moles and Mg atoms in POSS to prepare polyhedral oligomeric silsesquioxane / Mg mixture; (4). The mixture of polyhedral ...

Embodiment 3

[0039] (1). After mixing 1.0 g of porous carrier titanium dioxide with a pore diameter of 1 μm and 6 mmol of ethanol in 20 mL of tetrahydrofuran (THF) solution for 6 hours, an alcohol-modified porous carrier was obtained, and washed with 20 mL of THF to obtain an alcohol-modified porous carrier for 5 times , to obtain a porous carrier adsorbed by ethanol; (2). The organic substituents of polyhedral oligomerization silsesquioxane (POSS) molecules are substituted with isopropyl and hydroxyl groups, wherein one POSS molecule contains one hydroxyl group , to obtain modified polyhedral oligomerized silsesquioxane molecules, POSS molecular diameter is 20nm; (3). The modified polyhedral oligomerized silsesquioxane molecules in step (2) are mixed with 3mmol magnesium hydroxide ( Ethanol and magnesium molar ratio are 2) according to the mol ratio of hydroxyl molar number and Mg atom in POSS, be 10%, mix in 20mLTHF, prepare polyhedral oligomeric silsesquioxane / Mg mixture; (4). Step (3) ...

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