Reactor for propylene polymerization and process for producing propylene polymer

Abstract

A propylene polymerization reaction apparatus and a production method of a propylene-based polymer are capable of producing a continuous multi-stage polymer in low cost, high productivity and stably, and significantly reducing generation amount of an off-specification product accompanying change of polymerization condition, in multi-stage continuous vapor phase polymerization method of a propylene-based polymer using a catalyst for olefin polymerization. A reaction apparatus for producing a propylene-based polymer by a multi-stage continuous vapor phase polymerization method is used. One or more reactor of a horizontal-type reactor having inside a stirring machine which rotates around a horizontal axis, and a continuous stirred tank reactor to be connected to the horizontal-type reactor are provided, and a production method of a propylene-based polymer using the same.

Description

[0001]This application is a U.S. national stage application of International Application No. PCT / JP2010 / 069752 filed Nov. 5, 2010. The contents of which are hereby incorporated by reference in their entirety.TECHNICAL FIELD[0002]The present invention relates to a propylene polymerization reaction apparatus and a production method of a propylene-based polymer, and in more detail, the present invention relates to a propylene polymerization reaction apparatus and a production method of a propylene-based polymer, which are capable of producing a high quality continuous multi-stage polymer in low cost, high productivity and stably, in multi-stage continuous vapor phase polymerization method of a propylene-based polymer using a catalyst for olefin polymerization.[0003]In more detail, the present invention relates to a propylene polymerization reaction apparatus and a production method of a propylene-based polymer, which are capable of significantly reducing generation amount of an off-spe...

AI Technical Summary

Benefits of technology

[0062]According to the first aspect of the present invention, there is effect that it is a production apparatus which is capable of producing a continuous multi-stage polymer of a propylene-based polymer in minimal capital investment cost, and by stably maintaining high productivity.

[0063]In addition, according to the second aspect of the present invention, in the case of changing residence time in a specific vapor phase polymerization reaction tank in the multi-stage continuous vapor phase polymerization method, adjustment thereof becomes extremely easy (short time), as a result, there is effect that it is a production apparatus which is capable of producing by significantly reducing generation amount of an off-specification product accompanying with change of polymerization condition.

[0064]In addition, according to the third to the fifth aspects of the present invention, there is effect that they are manufacturing apparatuses which are capable of efficiently producing a propylene-based block polymer, which has superior balance of rigidity / impact resistance at low temperature, as well as suppressing generation of gel and high fluidity, which is suitable for automotive exterior material or the like. In addition, there is effect that they are manufacturing apparatuses enabling to supply the propylene-based block copolymer which is cheaper and stable in quality, because of a continuous vapor phase polymerization method.

[0065]In addition, according to the sixth to the eighth aspects of the present invention, there is effect that they are manufacturing apparatuses which are capable of stably and efficiently producing, by suppressing adhesion in the reaction tank, a propylene-based block polymer, which has superior balance of rigidity / impact resistance, as well as suppressing generation of gel, which is suitable for automotive members or electric appliance members and the like. Additionally, there is effect that they are manufacturing apparatus enabling to supply the propylene-based block copolymer which is cheaper and stable in quality, because of a continuous vapor phase polymerization method.

[0066]In addition, by installing two or more continuous stirred tank reactors, not only increase in content of the copolymer component of the propylene-based block copolymer becomes easy but also in the case of producing the copolymer component in two or more tanks, by making the copolymer component having different content of the α-olefin and / or molecular weight in each tank, there is effect that they are manufacturing apparatus enabling to attain further quality enhancement and diversity.

[0067]In addition, according to the ninth to the twelfth aspects of the present invention, there is effect that they are production apparatus which are capable of efficiently producing a propylene-based block polymer, which has superior balance of rigidity / impact resistance, as well as suppressed generation of gel and gloss, which is suitable for automotive exterior material or the like. In addition, there is effect that they are manufacturing apparatus enabling to supply the propylene-based block copolymer which is cheaper and stable in quality, because of a continuous vapor phase polymerization method.

Problems solved by technology

However, because of limited applications as a simple substance of polypropylene, various improvements have been added.

However, because polymer particles become nearly a completely mixed state in one container, short pass where not sufficiently grown particles are exhausted, or accumulation of too grown particles inside the container easily occurs, thus causing decrease in quality of said polymer.

To solve this, it is also considered to attain plug flow as a whole by connecting a plurality of continuous stirred tank reactors in series, however, installment of many reactors requires equipment cost.

As a result, in a process including the horizontal-type reactor, a problem of significant decrease in productivity in view of heat removal is raised, in producing a multi-stage polymer containing a component having low molecular weight, or a component such as ethylene.

To solve the above problems, there is also a method for enhancing cooling capability of a heat exchanger, however, that case requires tremendous equipment cost.

Provided that the heat exchanger having high capability is installed, its operation requires tremendous energy.

In this way, although a horizontal-type vapor phase method process has superior plug flow characteristics, the case of producing a multi-stage polymer having a component containing low molecular weight, or a component having ethylene or the like in high content has a problem to be solved in view of productivity and operation cost.

In addition, crystalline polypropylene is cheap and has superior characteristics in rigidity and heat resistance, however, had a problem that impact strength, in particular, impact strength at low temperature is weak.

However, these methods not only increase gel in the propylene-based block copolymer, and deteriorate appearance of a product caused by a large quantity of gel but also cause to decrease impact resistance.

However, a batch method has a problem of being inferior in view of economical efficiency and productivity.

As a method for producing a propylene-based block copolymer having low gloss by the multi-stage continuous vapor phase polymerization method, there has been disclosed a method for increasing molecular weight of the amorphous propylene / α-olefin copolymer or content of the α-olefin (for example, refer to PATENT LITERATURE 2 and 3), however, because the first stage polymerization step is performed in the continuous stirred tank reactor, there is left a problem in view of suppression of gel.

This method is advantageous in view of suppression of gel, because of narrow residence time distribution in a reaction tank, which enables to reduce bypassing particles in one reaction tank, however, has a problem of generation of composition distribution and easy providing high gloss in producing the amorphous propylene / α-olefin copolymer, because of removing heat of polymerization by latent heat of vaporization of liquid propylene, causing a non-uniform gas composition in a reactor.

This method improves as for suppression of gel, however, requires installment of many reactors, as well as has a problem of inability of producing desired amount of a copolymer in the second stage polymerization step, because of longer residence time in the first stage polymerization step, which decreases capability of a catalyst.

For example, to obtain a polymer having desired molecular weight, generally hydrogen is used in many cases as a molecular weight modifier, however, in the case of supplying a large quantity of hydrogen to obtain a polymer with low molecular weight in the first stage polymerization step, even trying to obtain a copolymer with high molecular weight without supplying hydrogen in the second stage polymerization step, hydrogen in entrained gas from a reactor of the first stage polymerization step inevitably flows into a reactor of the second stage polymerization step, resulting in generation of limitation in molecular weight of a copolymer formed in the second stage polymerization step.