Preparation method of polypropylene with high melt strength

A high melt strength, polypropylene technology, applied in the field of polypropylene preparation, can solve problems such as strong complexing ability, and achieve the effects of easy operation, broad application prospects, and high melt strength

Active Publication Date: 2014-05-14
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method also has the disadvantage that the first external electron donor has a strong complexing ability with the active center of the catalyst, while the second external electron donor needs to be used in large quantities to exert its effect.

Method used

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  • Preparation method of polypropylene with high melt strength
  • Preparation method of polypropylene with high melt strength
  • Preparation method of polypropylene with high melt strength

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] The polymerization reaction was carried out on a set of 25Kg / hr polypropylene pilot plant. Its main equipment includes prepolymerization reactor, first loop reactor and second loop reactor. Polymerization method and steps are as follows:

[0045] Step I

[0046] Prepolymerization:

[0047]The main catalyst (DQ-III catalyst, provided by Beijing Aoda Branch of Sinopec Catalyst Company), co-catalyst (triethylaluminum), and the first external electron donor (dicyclopentyldimethoxysilane) were tested at 6°C for 20min After pre-contact, continuously add to the continuous stirred tank pre-polymerization reactor for pre-polymerization reactor, the flow rate of triethylaluminum (TEA) entering the pre-polymerization reactor is 6.33g / hr, dicyclopentyldimethoxysilane (DCPMS) flow rate is 0.63g / hr, main catalyst flow rate is 0.01g / hr, TEA / DCPMS ratio is 20 (molar ratio), wherein DCPMS is the first external electron donor. The prepolymerization is carried out in the bulk environm...

Embodiment 2

[0056] Step is with embodiment 1, difference is: in the first loop reactor of step i, add a small amount of hydrogen, the hydrogen concentration that online chromatography detects is 300ppmV, the hydrogen concentration in the second loop reactor of step Ⅲ changes 1000ppmV. Polymerization process conditions, obtained polymer analysis results and polymer physical properties are listed in Tables 1-3.

Embodiment 3

[0058] Step is the same as Example 2, and the difference is: the ratio of aluminum alkyl and external electron donor in the reactor in the two steps is adjusted, and TEA / DCPMS is adjusted to 60 (molar ratio) in the first reactor of step i ), the TEA / DIBMP in the second reactor is adjusted to 10 (molar ratio), and the hydrogen concentration in the second loop reactor of step Ⅲ is changed to 5000ppmV. Polymerization process conditions, obtained polymer analysis results and polymer physical properties are listed in Tables 1-3.

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Abstract

The invention discloses a preparation method of polypropylene with high melt strength. The method includes i) a step of, under the action of a Ziegler-Natta catalyst containing a silane type external electron donor, subjecting propylene or propylene with other alpha-olefin to polymerization to obtain a polymer A having a melt mass flow rate of 0.01-0.4 g / min, with a hydrogen concentration being not more than 400 ppmV; ii) a step of adding a 1,3-diether type external electron donor and premixing the 1,3-diether type external electron donor and the polymer A; iii) a step of, under the existence of hydrogen and the premixed materials in the step ii), subjecting the propylene or the propylene with other alpha-olefin to polymerization to obtain a polymer B having a melt mass flow rate of 1.0-60 g / 10min; and a step of preparing polypropylene C with high melt strength comprising the polymer A and the polymer B. The melt mass flow rate of the polypropylene C is 0.8-15 g / 10min. The preparation method is simple and feasible and is convenient to operate and prone to industrial production. High-performance products with high melt strength and wide molecular weight distribution can be prepared by the method. The method has wide application prospect.

Description

technical field [0001] The invention relates to a method for preparing polypropylene, in particular to a method for preparing polypropylene with wide molecular weight distribution and high melt strength. Background technique [0002] Due to its high melt strength, yield strength, flexural modulus, heat distortion temperature, melting point, crystallization temperature and short crystallization time, high melt strength polypropylene is widely used in thermoforming, foaming, extrusion coating and other fields. Has been widely used. In these applications, the use of high melt strength polypropylene for thermoforming can make the parts demould at a higher temperature, shorten the molding cycle, and increase the output; Bubble magnification, reduce density, increase closed cell ratio; exhibit faster coating speed and small necking during extrusion coating. Therefore, high melt strength polypropylene is the research focus of polypropylene production technology innovation. The s...

Claims

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Application Information

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IPC IPC(8): C08F110/06C08F210/06C08F4/646C08F4/649
Inventor 宋文波毕福勇张晓萌魏文骏郭梅芳张师军
Owner CHINA PETROLEUM & CHEM CORP
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