A kind of preparation method of linear low density polyethylene

A linear low density, polyethylene technology, applied in the field of preparation of linear low density polyethylene, can solve the problems of poor copolymerization ability of active centers, uneven composition distribution of copolymerization products, etc., and achieves easy production process, low production cost, and insertion amount. high effect

Active Publication Date: 2017-07-14
SINOPEC YANGZI PETROCHEM +1
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  • Abstract
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  • Application Information

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Problems solved by technology

However, there are multiple active centers in the supported Ziegler-Natta catalyst, and the copolymerization ability of the active center is poor, which makes the amount of comonomer used in the preparation of LLDPE by the supported Ziegler-Natta catalyst far greater than The amount of intercalated comonomer in the final copolymer, and the composition distribution of the copolymerized product is very uneven

Method used

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  • A kind of preparation method of linear low density polyethylene
  • A kind of preparation method of linear low density polyethylene
  • A kind of preparation method of linear low density polyethylene

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preparation example Construction

[0019] The preparation method of the pre-activated catalyst is: under the condition of anhydrous and oxygen-free, about 1g of supported TiCl 4 / MgCl 2 Add the catalyst into a 50ml Schlenk bottle, add 30ml of n-heptane refluxed with a potassium-sodium alloy, add the corresponding alkylaluminum according to the designed aluminum-titanium ratio, and stir and react at 20-50°C for 10-120min. After standing for precipitation, separate the supernatant, then add 20ml of n-heptane that has been refluxed with a potassium-sodium alloy to wash the catalyst, stir for 1-5min, set aside for precipitation, and separate the supernatant. Finally, the solvent was drained, and the obtained catalyst was transferred to a glove box for future use.

[0020] The specific conditions of the polymerization reaction include: the concentration of Ti in the polymerization system (calculated according to the ratio of the number of moles of Ti in the main catalyst added to the amount of solvent used) is 2×10...

Embodiment 1

[0024] Preactivation of supported TiCl with trimethylaluminum 4 / MgCl 2 Catalyst, the amount of trimethylaluminum is added according to Al / Ti=1, obtains the pre-activated loaded TiCl 4 / MgCl 2 Catalyst (Catalyst 1). With 17mg of catalyst 1 as the main catalyst, triisobutylaluminum (Al / Ti=100) as the cocatalyst, and 100mL of n-heptane as the solvent, add 5% (volume fraction) H 2 , the concentration of 1-hexene is 0.4mol / L, and the slurry polymerization of ethylene and 1-hexene is catalyzed at 50°C and 0.4MPa to obtain 10.4g copolymerized product, and the molar content of 1-hexene in the product is 5.1%.

Embodiment 2

[0026] Preactivation of supported TiCl with triethylaluminum 4 / MgCl 2 Catalyst, the amount of triethylaluminum is added according to Al / Ti=2, obtains the pre-activated loaded TiCl 4 / MgCl 2 Catalyst (Catalyst 2). With 17mg of catalyst 2 as the main catalyst, triisobutylaluminum (Al / Ti=100) as the cocatalyst, 100mL of n-heptane as the solvent, adding 10% (volume fraction) H 2 , the concentration of 1-octene is 0.4mol / L, catalyzed the slurry polymerization of ethylene and 1-octene at 50°C and 0.4MPa to obtain 11.7g copolymerization product, the molar content of 1-octene in the product is 4.2%.

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Abstract

The invention discloses a preparation method of linear low density polyethylene. By using an alkylaluminium-preactivated supported TiCl4 / MgCl2 catalyst as a main catalyst, using alkylaluminium as a cocatalyst and using H2 as a molecular weight modifier, ethene and alpha-olefin undergo a slurry polymerization reaction so as to obtain the linear low density polyethylene. The preparation method of the linear low density polyethylene is suitable for a production device of linear low density polyethylene with the supported TiCl4 / MgCl2 catalyst used as a main catalyst. In comparison with a metallocene catalysis system, the production process of the invention is easy to control, use amount of the cocatalyst is low, production cost is low, insert quantity of alpha-olefin in the prepared linear low density polyethylene is high, composition and distribution of a copolymer are uniform, tensile property of the copolymer is good, and the copolymer has better application characteristics.

Description

technical field [0001] The invention relates to a preparation method of linear low-density polyethylene. Background technique [0002] Polyethylene products are currently the polymer species with the largest output, and the most widely used one is linear low-density polyethylene (LLDPE), which is obtained by copolymerization of ethylene and α-olefin. There are two types of catalytic systems for producing LLDPE: supported Ziegler-Natta catalysts and metallocene catalysts. The metallocene catalyst has high polymerization activity, and the prepared LLDPE has a narrow molecular weight distribution and a uniform composition distribution. Chinese patent CN102190749 relates to a configuration-limited carbon-bridged single metallocene catalyst, which exhibits high polymerization activity when catalyzing the copolymerization of ethylene with α-olefins such as 1-hexene or 1-octene, and the α - Higher content of olefins. Chinese patent CN102101899 relates to a metallocene catalyst c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C08F210/02C08F4/655C08F2/06
Inventor 胡庆云范志强傅智盛笪文忠梅利李栋王兴仁
Owner SINOPEC YANGZI PETROCHEM
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