CN111560091A - Production process of random copolymerization polypropylene - Google Patents
Production process of random copolymerization polypropylene Download PDFInfo
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- CN111560091A CN111560091A CN202010476962.XA CN202010476962A CN111560091A CN 111560091 A CN111560091 A CN 111560091A CN 202010476962 A CN202010476962 A CN 202010476962A CN 111560091 A CN111560091 A CN 111560091A
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- propylene
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F210/04—Monomers containing three or four carbon atoms
- C08F210/06—Propene
Abstract
The invention discloses a production process of random copolymerization polypropylene, which belongs to the technical field of high polymer materials, wherein propylene, hydrogen and ethylene enter an external circulation fan and a condenser for condensation, condensate liquid returns to a polymerization kettle, polymerization heat is taken away through repeated gasification and condensation of the propylene, the polymerization heat of the propylene is removed through jacket heat removal, evaporation heat and external circulation fan of liquid phase propylene, when a random copolymerization product is produced, ethylene is added through two gas phase external circulation fans, a cooling means, namely a circulation system, is added, and the circulation heat removal capability of a polymerization system is improved; the second reactor is a plug flow reactor, so that the reaction is stable and the materials are not back-mixed; the SPG process device is utilized to realize the development of the random copolymerization polypropylene product with stable quality and excellent performance.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and particularly relates to a production process of random copolymerization polypropylene.
Background
The polypropylene random copolymer is one kind of polypropylene, and its basic structure of high molecular chain is modified by adding different kinds of monomer molecules. Ethylene is the most commonly used monomer, which causes a change in the physical properties of polypropylene. Compared with PP homopolymer, the random copolymer has excellent optical property, impact resistance, flexibility and the like, and the melting temperature is reduced, so that the thermal welding temperature is also reduced; while being substantially the same as the homopolymer in terms of chemical stability, water vapor barrier properties and organoleptic properties (low odor and taste). The method can be applied to the fields of blow molding, injection molding, extrusion molding, film and sheet extrusion processing, and is mainly applied to tap water pipes, food packaging materials, medicine packaging materials and daily consumer goods. Therefore, the development of the random copolymerization polypropylene with stable quality and excellent performance has important significance for improving the grade and comprehensive competitiveness of enterprise products.
Disclosure of Invention
The invention aims to provide a production process of random copolymerization polypropylene, which improves the cyclic heat removal capability, has stable reaction and no back mixing of materials, and has stable output quality and excellent performance.
In order to solve the technical problems, the invention adopts the technical scheme that: a production process of random copolymerization polypropylene comprises the following steps:
firstly, carrying out liquid-phase bulk prepolymerization on propylene in a prepolymerization kettle under the action of a catalyst and a molecular weight regulator;
step two, entering a first reactor, and carrying out slurry polymerization in liquid propylene;
thirdly, the propylene, the hydrogen and the ethylene which leave the first reactor enter an external circulation fan and a condenser for condensation, the condensate returns to the polymerization kettle, and polymerization heat is taken away through repeated gasification and condensation of the propylene;
and step four, the propylene and polypropylene slurry leaving the first reactor enters a second reactor to carry out gas-phase polymerization by means of the pressure of the propylene and polypropylene slurry.
In the first step, continuous prepolymerization is adopted for prepolymerization, the residence time is 3-4 min, the prepolymerization pressure is 3.15-4.01 MPa, and polymerization is carried out at normal temperature.
In the second step, the polymerization pressure is 3.1-3.96 MPa, the temperature is 70 ℃, and the retention time is 45 min.
In the third step, the heat of polymerization of propylene is removed by the jacket of liquid phase propylene, the heat of evaporation and the heat removal of the external circulation fan, and when the random copolymerization product is produced, ethylene is added by two gas phase external circulation fans.
In the fourth step, the second reactor is a plug flow reactor, the reaction is stable, the materials are not back-mixed, the polymerization pressure is 2.6-2.8MPa, and the temperature is 60-80 ℃.
Compared with the prior art, the invention has the beneficial effects that:
the beneficial effects of the invention are as follows: (1) propylene, hydrogen and ethylene enter an external circulation fan and a condenser to be condensed, condensate returns to a polymerization kettle, polymerization heat is taken away through repeated gasification and condensation of the propylene, the polymerization heat of the propylene is removed through jacket heat removal, evaporation heat removal and external circulation fan heat removal of liquid-phase propylene, and when a random copolymerization product is produced, ethylene is added through two gas-phase external circulation fans. (2) The second reactor of the invention is a plug flow reactor, and the design can ensure that the reaction is stable and the materials are not back-mixed. (3) The invention utilizes the SPG process device to realize the development of the random copolymerization polypropylene product with stable quality and excellent performance.
Detailed Description
The invention is further described with reference to the following examples:
the invention provides a production process of random copolymerization polypropylene, which comprises the following steps: propylene is subjected to liquid-phase bulk prepolymerization in a prepolymerization kettle under the action of a catalyst and a molecular weight regulator, continuous prepolymerization is adopted in the prepolymerization, the residence time is 3 minutes, the prepolymerization pressure is 3.5MPa, the polymerization is carried out at normal temperature, then the propylene enters a first reactor, slurry polymerization is carried out in liquid propylene, the polymerization pressure is 3.8MPa, the temperature is 70 ℃, the residence time is 45min, the polymerization heat of the propylene is removed through a jacket of the liquid-phase propylene, evaporation heat and an external circulation fan, and ethylene is added through 2 gas-phase external circulation fans when a random copolymerization product is produced; the propylene, hydrogen and ethylene leaving the first reactor enter an external circulation fan and a condenser for condensation, condensate returns to a polymerization kettle, polymerization heat is taken away by repeated gasification and condensation of the propylene, propylene and polypropylene slurry leaving the first reactor enters a second reactor for gas phase polymerization by the pressure of the propylene and the polypropylene slurry, the second reactor is a plug flow reactor, the reaction is stable, the material is not back mixed, the polymerization pressure is 2.7MPa, and the temperature is 70 ℃.
The catalyst is alkyl aluminum and silane, and the molecular weight regulator is hydrogen.
The following are the main technical indicators of the embodiment:
| number plate | Melt index g/10mins | Isotactic degree% | Yield strength MPa | Ash content PPM | Use of |
| R002A | ≤0.10 | 94 | 28 | 200max | Extrusion material |
| R002 | 0.11-0.20 | 94 | 28 | 200max | Extrusion material |
| R005 | 0.21-0.50 | 94 | 26 | 200max | Pipe material |
| R007 | 0.51-0.70 | 94 | 26 | 200max | Sheet material |
| R012 | 0.71-2.5 | 94 | 26 | 200max | Drawing wire |
| R045 | 2.51-6.0 | 94 | 26 | 200max | Drawing wire |
Propylene, hydrogen and ethylene enter an external circulation fan and a condenser to be condensed, condensate returns to a polymerization kettle, polymerization heat is taken away through repeated gasification and condensation of the propylene, the polymerization heat of the propylene is removed through jacket heat removal, evaporation heat removal and external circulation fan heat removal of liquid-phase propylene, and when a random copolymerization product is produced, ethylene is added through two gas-phase external circulation fans.
The second reactor of the invention is a plug flow reactor, and the design can ensure that the reaction is stable and the materials are not back-mixed.
The catalyst is premixed, the alkyl aluminum and the silane are already deeply inserted into the catalyst, and the aluminum/titanium ratio and the aluminum/silicon ratio of the catalyst inside and the catalyst surface are the same, so that the isotacticity and the uniformity of the product are improved. After mixing the catalyst with propylene, a small amount of polymerization occurs, forming a polypropylene mesh around the catalyst particles and inside the capillaries. This polypropylene mesh protects the catalyst when it enters the slurry reactor. If the catalyst enters the slurry reactor directly without forming such a polypropylene mesh, the catalyst particles become sticky and may also explode, resulting in a very fine powder.
The invention utilizes the SPG process device to realize the development of the random copolymerization polypropylene product with stable quality and excellent performance.
The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention should be covered by the present patent.
Claims (5)
1. A production process of random copolymerization polypropylene is characterized in that: the method comprises the following steps:
firstly, carrying out liquid-phase bulk prepolymerization on propylene in a prepolymerization kettle under the action of a catalyst and a molecular weight regulator;
step two, entering a first reactor, and carrying out slurry polymerization in liquid propylene;
thirdly, the propylene, the hydrogen and the ethylene which leave the first reactor enter an external circulation fan and a condenser for condensation, the condensate returns to the polymerization kettle, and polymerization heat is taken away through repeated gasification and condensation of the propylene;
and step four, the propylene and polypropylene slurry leaving the first reactor enters a second reactor to carry out gas-phase polymerization by means of the pressure of the propylene and polypropylene slurry.
2. The random copolymer polypropylene production process according to claim 1, wherein: in the first step, continuous prepolymerization is adopted for prepolymerization, the residence time is 3-4 min, the prepolymerization pressure is 3.15-4.01 MPa, and polymerization is carried out at normal temperature.
3. The random copolymer polypropylene production process according to claim 1, wherein: in the second step, the polymerization pressure is 3.1-3.96 MPa, the temperature is 70 ℃, and the retention time is 45 min.
4. The random copolymer polypropylene production process according to claim 1, wherein: in the third step, the heat of polymerization of propylene is removed by the jacket of liquid phase propylene, the heat of evaporation and the heat removal of the external circulation fan, and when the random copolymerization product is produced, ethylene is added by two gas phase external circulation fans.
5. The random copolymer polypropylene production process according to claim 1, wherein: in the fourth step, the second reactor is a plug flow reactor, the reaction is stable, the materials are not back-mixed, the polymerization pressure is 2.6-2.8MPa, and the temperature is 60-80 ℃.
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| CN202010476962.XA CN111560091A (en) | 2020-05-29 | 2020-05-29 | Production process of random copolymerization polypropylene |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040122191A1 (en) * | 2002-09-20 | 2004-06-24 | Palanisamy Arjunan | Supercritical polymerization process and polymers produced therefrom |
| CN101618310A (en) * | 2009-07-27 | 2010-01-06 | 南京金陵塑胶化工有限公司 | Polymeric kettle and thermal withdrawal mode thereof |
| CN109776701A (en) * | 2017-11-10 | 2019-05-21 | 北京华福工程有限公司 | Propylene homo or the method for random copolymerization |
| CN110918018A (en) * | 2019-10-18 | 2020-03-27 | 中国石油化工股份有限公司 | Combined heat removal method for kettle type slurry polyethylene reactor |
-
2020
- 2020-05-29 CN CN202010476962.XA patent/CN111560091A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040122191A1 (en) * | 2002-09-20 | 2004-06-24 | Palanisamy Arjunan | Supercritical polymerization process and polymers produced therefrom |
| CN101041701A (en) * | 2002-09-20 | 2007-09-26 | 埃克森美孚化学专利公司 | Polymer containing propylene and its use |
| CN101618310A (en) * | 2009-07-27 | 2010-01-06 | 南京金陵塑胶化工有限公司 | Polymeric kettle and thermal withdrawal mode thereof |
| CN109776701A (en) * | 2017-11-10 | 2019-05-21 | 北京华福工程有限公司 | Propylene homo or the method for random copolymerization |
| CN110918018A (en) * | 2019-10-18 | 2020-03-27 | 中国石油化工股份有限公司 | Combined heat removal method for kettle type slurry polyethylene reactor |
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