JP2000017005A - Continuous pre-polymerization apparatus for polyolefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the subject apparatus capable of preventing a blockade due to the deposits of polymers, by using a tubular-type reactor comprising an inner fluororesin tube and an outer metal tube. SOLUTION: A continuous pre-polymerization apparatus for polyolefin comprising a 5 to 100 m-long, tubular-type reactor, is obtained by bonding an outer tube 2 made of one or more kinds of metals selected from SUS 304 seamless pipe, SUS 316 seamless pipe, carbon steel pipe, SUS 304 steel pipe, and SUS 316 steel pipe, closely onto an outside of an inner tube 1 having an inner dia. of 3-20 mmϕ made of one or more kinds of fluororesins selected from 4- fluoroethylene resin, 4-fluoroethylene/perfluoroethylene copolymer resin, 4- fluoroethylene/6-fluoropropylene copolymer resin, and 3-fluorochloroethylene, and if necessary by forming into a coil form or a wave form.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a continuous prepolymerization apparatus for polyolefin. Specifically, this is a device that continuously supplies a pre-polymerized supported solid catalyst to the present polymerization device,
The present invention relates to a continuous prepolymerization apparatus for polyolefin using a tubular reactor in which blockage due to adhesion of a polymer is prevented.

[0002]

2. Description of the Related Art Conventionally, in an industrial production method of polyolefins such as polyethylene and polypropylene, prepolymerization is carried out during bulk polymerization or gas phase polymerization using a Ziegler type catalyst in which a titanium halide is supported on a carrier such as magnesium chloride. The use of a catalyst has suppressed the generation of polymer fines and polymer lumps.

[0003] That is, if a catalyst that is not prepolymerized is used as it is, the reaction proceeds rapidly in the initial stage during the process in which the polymer grows spherically around the catalyst particles, so that destruction and fusion of the spherical polymer occur. That's why. If a large amount of such fine powders or lumps is generated, clogging of pipes and troubles in quality may occur, so that some proposals regarding a prepolymerization method have been made so far. Among them, a method of continuously performing prepolymerization using a tube-type prepolymerizer is disclosed in, for example, JP-A-61-66705 and JP-A-2001-66705.
JP-A-135804, JP-A-07-62017 and JP-A-08-183809.

However, there is no disclosure of the specific structure, material, etc. of the prepolymerization device for preventing the adhesion of the polymer. On the other hand, in pipes for transferring a reactant or a substance having a high viscosity, a steel pipe whose inner wall is coated with a fluororesin or a pipe in which a reinforcing mesh is wound around a fluororesin tube is known. For use in a tubular prepolymerizer, severe conditions such as high-pressure, high-speed continuous slurry transportation are required, and it is not sufficiently durable.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for continuously supplying a catalyst such as a pre-polymerized supported solid catalyst to a main polymerization apparatus for polyolefin, wherein a tubular reaction in which blockage due to adhesion of a polymer is prevented. It is intended to provide a container structure.

[0006]

The gist of the present invention is as follows. [1] A continuous prepolymerization apparatus for polyolefin, wherein a tubular reaction tube comprising an inner tube of a fluororesin tube and an outer tube of a metal tube is used. [2] The continuous prepolymerization apparatus for polyolefin according to [1], wherein a tubular reaction tube comprising an outer tube in which an integral inner tube and a plurality of metal tubes are joined is used. [3] The fluororesin tube is made of ethylene tetrafluoride resin (PTFE), ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer resin (PFA), and ethylene tetrafluoride-propylene hexafluoride copolymer resin (FEP). ), The continuous prepolymerization apparatus for polyolefins according to the above [1] or [2], comprising one or a combination of two or more kinds of fluorine-based resins selected from ethylene trifluorochloride resin (PCTFE). [4] Metal tubes are SUS304 seamless tube, SUS316 seamless tube, carbon steel tube, S
The above [1] to [3], which are one kind or a combination of two or more kinds selected from US304 steel pipe and SUS316 steel pipe.
A continuous prepolymerization apparatus for a polyolefin according to any one of the above. [5] The continuous prepolymerization apparatus for polyolefin according to any one of the above [1] to [4], wherein the tubular reactor is formed in a coil shape. [6] The above [1] to [1] to wherein the tubular reactor is formed in a wave shape
The continuous prepolymerization apparatus for polyolefin according to any one of [4]. [7] The continuous prepolymerization apparatus for polyolefin according to any one of [1] to [6] above, wherein the tubular reaction tube is connected to a gas phase polymerization reactor. [8] The continuous prepolymerization apparatus for polyolefin according to any one of the above [1] to [7], further comprising a jacket for passing a refrigerant outside the tubular reaction tube.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific example of the present invention will be described with reference to the drawings. FIG. 1 shows a tubular reaction tube according to the present invention comprising an inner tube (1) of a fluororesin tube and an outer tube (2) of a metal tube. The tubular reaction tube has a structure in which an inner tube (1) of a fluororesin tube is supported by an outer tube (2) of a metal tube closely attached to the outside thereof so that the tube can sufficiently withstand internal pressure. Has become.

Further, as shown in FIGS. 2 and 3, the fluororesin tube used for the inner tube (1) is preferably a long one-piece tube, and the outer tube (2) of the metal tube is
What consists of a plurality of outer tubes and joints (3, 4) is preferred. Usually, a tubular reaction tube is provided between the solid catalyst supply tank and the main polymerization reactor, and is provided under predetermined prepolymerization conditions, for example, under the prepolymerization conditions disclosed by the present applicant in JP-A-10-120719. The length of the tube is determined so that the catalyst component is mixed with unreacted liquid propylene at an average flow rate of 0.3 m / sec or more and the average residence time in the prepolymerizer is 25 seconds or less. The length of the tubular reaction tube is preferably 5 to 100.
m. The inner diameter of the pipe is determined by the flow rate of liquid propylene, and is preferably 3 to 20 mmφ.

The fluororesin tube used for the inner tube (1) is preferably a tube having a length equal to the total length of the tube type reaction tube, and an outer tube (2) of a plurality of metal tubes from one end of the tube. And connect the outer tubes to each other with a splicer (3,
By joining in step 4), a tubular reaction tube can be easily assembled. In addition, the fitting shown in FIG. 2 (for example, a straight union made by Fujikin) is used for this splicer.
And the flange shown in FIG. Above all, the fitting is particularly easy to operate and can be suitably used.

As the tubular reaction tube, in addition to a straight tube type, a coiled type (FIG. 5) and a corrugated type (FIG. 6) can be used. Both have the advantage that the installation space can be used compactly, and external cooling can be easily performed by putting the whole in a refrigerant tank (water tank or the like). Further, as a fluororesin tube used for the inner pipe (1), an ethylene tetrafluoride resin (P
TFE), ethylene tetrafluoride-perfluoroalkyl vinyl ether copolymer resin (PFA),
A tube formed by extrusion or the like using one or a combination of two or more fluororesins selected from propylene hexafluoride copolymer resin (FEP) and ethylene trifluorochloride resin (PCTFE) is used.

The above-mentioned fluororesin tube is an integral member in addition to the inherent properties of the material, so there is no trouble such as leakage from the seam or peeling of the coating, it can withstand continuous use for a long time, and the polymer in the reaction tube can be used. Effective for preventing adhesion of Further, as a metal tube used for the outer tube (2), SUS304 seamless tube, SU
S316 seamless tube, carbon steel tube, SUS304
One or two or more combination tubes selected from steelmaking pipes and SUS316 steelmaking pipes are used. The role of the outer tube is to maintain the pressure applied to the inner tube and also to remove the heat of reaction (exothermic reaction), and to exchange heat with an external refrigerant (water, etc.) by attaching a jacket as shown in FIG. Can also.

[0012]

The present invention will be described in further detail with reference to examples. Example A polypropylene was produced by a gas phase polymerization method using an apparatus as shown in FIG. As the prepolymerizer (8), a tubular reactor without a refrigerant jacket as shown in FIGS. 1 and 2 was used. Details of the structure are as follows: inner diameter 4 mm, outer diameter 6 mm, length 22.5
PTFE tube (PTFE) with a diameter of 6 meters and 22 SUS304 seamless tubes with an inner diameter of 6 mm, an outer diameter of 8 mm and a length of 1 meter and an inner diameter of 6
SUS304 seamless tube having a diameter of 8 mm and an outer diameter of 8 mm and a length of 0.2 m was used.
Were joined using 22 straight unions, so that the entire length of the outer tube was the same as the entire length of the inner tube, and the entire shape was coiled.

Using a 200-liter capacity polymerization reactor (7), a solid catalyst supporting titanium tetrachloride on magnesium (5)
Is converted to the number of grams of titanium, at a rate of about 0.04 g / hour, 45.0 kg / hour of liquid propylene (6), and 225 mmol / hour of triethylaluminum as a cocatalyst (10). Electron donating compound (1
As 1), dicyclopentyldimethoxysilane was supplied to the prepolymerizer (8) so that the supply molar ratio of the two was 4: 1. The average flow rate of the liquid propylene in the prepolymerizer (8) is 1.5 m / sec, the average residence time is 15 seconds, the temperature at the inlet to the main polymerizer is 10 ° C, and the amount of prepolymerization is Is 0.8 g per 1 g of the solid catalyst component (titanium tetrachloride-supported magnesium catalyst), and is 0.004% by weight of liquid propylene.

As a molecular weight regulator, hydrogen gas was supplied from the line (9) at 1800 liter / hour. The heat of polymerization can be removed from the external circulation line (1) through the polymerization vessel (7).
The gas extracted using 3) was cooled by a heat exchanger (14), and the gas was recycled from the lower part of the main polymerization reactor (7). The main polymerization unit (7) has a pressure of 30 kg / c.
Polymerization was carried out under the conditions of m ² G and a polymerization temperature of 80 ° C., and the produced powder (12) was taken out of the system together with the accompanying gas through a line. As a result of the above polymerization, the obtained polypropylene was produced at a rate of 32.3 kg / hour.

After the continuous operation for 7 days, the prepolymerizer was removed for confirmation, and the inside was examined. No deposit was found at all.

[0016]

The use of the continuous prepolymerization apparatus for polyolefins of the present invention suppresses the formation of deposits in the prepolymerizer and enables long-term continuous operation. Conventionally, when operating with a prepolymerized tube (a SUS tube without an inner tube) that is usually used, the flow rate of propylene began to decrease 5 minutes after the start of operation, and was blocked after 20 minutes.

[0017]

[Brief description of the drawings]

FIG. 1 is a conceptual diagram (perspective view) of a tube reactor for prepolymerization in the present invention.

FIG. 2 is a conceptual diagram of a tube reactor for prepolymerization joined by fitting.

FIG. 3 is a conceptual diagram of a prepolymerization tube type reaction tube joined by a flange.

FIG. 4 is a flowchart of a gas phase polymerization apparatus for polypropylene.

FIG. 5: Tubular reaction tube for coiled prepolymerization

FIG. 6 is a tubular reactor for corrugated prepolymerization.

FIG. 7 is a conceptual diagram of a tube reactor for prepolymerization with a jacket for temperature control.

[Explanation of symbols]

 1: inner tube 2: outer tube 3: fitting (joining device) 4: flange (joining device) 5: solid catalyst 6: liquid propylene 7: main polymerization device 8: prepolymerization device 9: hydrogen gas 10: cocatalyst 11 : Electron donating compound 12: Generated powder 13: External circulation line 14: Heat exchanger 15: Refrigerant inlet 16: Refrigerant outlet 17: Liquid propylene containing solid catalyst 18: Liquid propylene containing prepolymerized solid catalyst 19: Temperature control jacket

Claims (8)

[Claims] An apparatus for continuous prepolymerization of polyolefin, wherein a tubular reaction tube comprising an inner tube of a fluororesin tube and an outer tube of a metal tube is used. 2. The continuous prepolymerization apparatus for polyolefins according to claim 1, wherein a tubular reaction tube comprising an integral inner tube and an outer tube in which a plurality of metal tubes are joined is used. 3. A fluororesin tube made of an ethylene tetrafluoride resin (PTFE), an ethylene tetrafluoride-perfluoroalkylvinyl ether copolymer resin (PFA), or a tetrafluoroethylene-hexafluoropropylene copolymer resin. (FE
The continuous prepolymerization apparatus for polyolefin according to claim 1 or 2, wherein the apparatus comprises one or a combination of two or more kinds of fluororesins selected from P) and chlorofluoroethylene resin (PCTFE). 4. The metal tube is one or a combination of two or more selected from SUS304 seamless tube, SUS316 seamless tube, carbon steel tube, SUS304 steel tube, and SUS316 steel tube.
A continuous prepolymerization apparatus for a polyolefin according to any one of the above. 5. The continuous prepolymerization apparatus for polyolefin according to claim 1, wherein the tubular reactor is formed in a coil shape. 6. The continuous prepolymerization apparatus for polyolefins according to claim 1, wherein the tubular reactor is formed in a corrugated form. 7. The continuous prepolymerization apparatus for polyolefins according to claim 1, wherein the tubular reaction tube is connected to a gas phase polymerization reactor. 8. The continuous prepolymerization apparatus for polyolefin according to claim 1, further comprising a jacket through which a refrigerant is passed outside the tubular reaction tube.