JP2013212995A - Method for producing olefin polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing oligomer (C20) in which the pyrolysis of the oligomer is suppressed and a yield is 0.99 or more when producing the oligomer (C20) having 20 carbon atoms from α-olefin of 10 carbon atoms.SOLUTION: A method for producing olefin polymers having 20 carbon atoms includes: polymerizing alpha-olefins having 10 carbon atoms to produce a polymerization liquid comprising polymers having 20 carbon atoms or more; removing unreacted alpha-olefins having 10 carbon atoms from the polymerization liquid; distilling the polymerization liquid; and separating, at a yield of 0.99 or more, olefin polymers having 20 carbon atoms in which the amount of a light component having 6 to 16 carbon atoms is 100 weight ppm or less.

Description

  The present invention relates to a method for producing an olefin polymer having 20 carbon atoms and an olefin polymer having 20 carbon atoms obtained by the production method.

An oligomer (C20) having 20 carbon atoms, which is a dimer produced from an α-olefin (C10) having 10 carbon atoms, is spreading to the market as a product centering on adhesives and sealing agents.
Since C20 is an olefin, it can be used as a reaction activator, has no volatile organic compound (VOC), and has low odor characteristics. Accordingly, when a light component, particularly a VOC component having a great influence on the human body or a VOC component of odorous olefins, is mixed, the product value is remarkably lowered. Therefore, it is necessary not to mix them in the manufacturing process.
In addition, although C20 itself of a product is an olefin, since it is a high boiling point and low volatility, it has almost no odor characteristic peculiar to an olefin.

  The polymerization reaction for producing C20 has been conventionally performed using various catalysts, but this reaction is a chain polymerization reaction regardless of the catalyst. That is, the polymerization product contains an oligomer (C30 +) having 30 or more carbon atoms as a by-product in addition to C20 as a product. Therefore, it is necessary to separate the product C20 and the by-product C30 +.

  In order to separate C20 in high yield and recover the tower top, it is necessary to raise the tower bottom temperature. However, if the tower bottom temperature is raised, VOC generated by thermal decomposition is mixed into C20 and the product quality deteriorates. I will let you. On the other hand, if the tower bottom temperature is lowered to prevent thermal decomposition, C20 is lost to the tower bottom, and the C20 yield is lowered.

JP 2006-232673 A

  An object of the present invention is to provide a method for producing C20 that suppresses thermal decomposition of an oligomer and produces a yield of 0.99 or more when producing an oligomer (C20) having 20 carbon atoms from an α-olefin having 10 carbon atoms. Is to provide.

As a result of intensive studies, the present inventors have found that control of thermal decomposition and securing of high yield can be achieved by controlling the bottom pressure of the distillation column.
According to the present invention, the following olefin polymer production methods and the like are provided.
1. A polymer solution containing a polymer having 20 or more carbon atoms is produced by polymerizing an α-olefin having 10 carbon atoms, and after removing the unreacted α-olefin having 10 carbon atoms from the polymer solution, the polymer solution is distilled. Then, a method for producing a olefin polymer having 20 carbon atoms, comprising separating a olefin polymer having 20 to 16 carbon atoms having a carbon content of 6 to 16 having a carbon content of 100 wt ppm or less in a yield of 0.99 or more. .
2. 2. The method for producing an olefin polymer having 20 carbon atoms according to 1, wherein the distillation is performed at 280 ° C. or lower.
3. 3. The method for producing an olefin polymer having 20 carbon atoms according to 1 or 2, wherein the distillation is performed in a distillation column equipped with a falling liquid film evaporator.
4). The method for producing an olefin polymer having 20 carbon atoms according to any one of 1 to 3, wherein the distillation is performed in a distillation column equipped with a tower top condenser of a distillation column internal heat exchanger type.
5. The method for producing an olefin polymer having 20 carbon atoms according to any one of 1 to 4, wherein the polymerization is performed in the presence of a metallocene catalyst.
The olefin polymer of carbon number 20 obtained by the manufacturing method in any one of 6.1-5.

  According to the present invention, when producing an oligomer (C20) having 20 carbon atoms from an α-olefin (C10) having 10 carbon atoms, thermal decomposition of the oligomer is suppressed, and the yield of C20 is set to 0.99 or more. A manufacturing method can be provided.

It is the schematic which shows an example of the distillation column used with the manufacturing method of this invention. It is the schematic which shows the distillation tower generally used.

In the first production method of the present invention, a polymer solution containing C20 + is produced by polymerizing C10, the polymer solution from which unreacted C10 has been removed is distilled, and C20 is separated at a yield of 0.99 or more.
At this time, the density | concentration of the C6-C16 light part produced | generated by thermal decomposition in isolate | separated C20 is 100 weight ppm or less.

  “C10” means an α-olefin (decene) having 10 carbon atoms, “CX” (X is an integer) means an olefin polymer having X carbon atoms, and “CX +” means a mixture of olefin polymers having X or more carbon atoms. To do.

  As a polymerization method for producing a polymerization liquid containing raw materials C10 to C20, a known method can be used.

  As the polymerization catalyst that can be used, a metallocene catalyst, a Ziegler-Natta catalyst, or the like can be used, and a metallocene catalyst is preferable. For example, a metallocene catalyst that is a transition metal compound and a catalyst that contains at least one selected from a compound that can react with the transition metal compound or a derivative thereof to form an ionic complex or an aluminoxane can be given. An organoaluminum compound can be used as the promoter component.

  Examples of the metallocene catalyst include transition metal compounds represented by the following formula (I).

(In the formula, M represents a metal element of Groups 3 to 10 of the periodic table or a lanthanoid series, and E ¹ and E ² are a cyclopentadienyl group, a substituted cyclopentadienyl group, an indenyl group, a substituted indenyl group, respectively. A ligand selected from a heterocyclopentadienyl group, a substituted heterocyclopentadienyl group, an amide group, a phosphide group, a hydrocarbon group, and a silicon-containing group, and is bridged via A ¹ and A ² Forms a structure, and they may be the same or different from each other, X represents a sigma-binding ligand, and when there are a plurality of Xs, the plurality of Xs may be the same or different. X, E ¹ , E ² or Y may be cross-linked.
Y represents a Lewis base, and when there are a plurality of Y, the plurality of Y may be the same or different, may be cross-linked with other Y, E ¹ , E ² or X, and A ¹ and A ² are A divalent bridging group that binds two ligands, a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, a silicon-containing group, a germanium-containing group, a tin-containing group , -O -, - CO -, - S -, - SO 2 -, - Se -, - NR 1 -, - PR 1 -, - P (O) R 1 -, - BR 1 - or -AlR ¹ - R ¹ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms or a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, which may be the same as or different from each other. q represents an integer of 1 to 5 and represents [(M valence) -2], and r represents an integer of 0 to 3. )

In the above formula (I), M represents a metal element of Groups 3 to 10 of the periodic table or a lanthanoid series, and specific examples include titanium, zirconium, hafnium, yttrium, vanadium, chromium, manganese, nickel, cobalt, palladium and Examples of these include lanthanoid metals, among which titanium, zirconium and hafnium are preferred from the viewpoint of olefin copolymerization activity.
E ¹ and E ² are preferably a cyclopentadienyl group, a substituted cyclopentadienyl group, or a substituted or unsubstituted indenyl group.

Specific examples of X include a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, an amide group having 1 to 20 carbon atoms, and a carbon number. Examples thereof include a silicon-containing group having 1 to 20, a phosphide group having 1 to 20 carbon atoms, a sulfide group having 1 to 20 carbon atoms, and an acyl group having 1 to 20 carbon atoms.
Specific examples of the Lewis base of Y include amines, ethers, phosphines, thioethers and the like.

Next, A ¹ and A ² are divalent bridging groups for bonding two ligands, which are a hydrocarbon group having 1 to 20 carbon atoms, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, and a silicon-containing group. Group, germanium-containing group, tin-containing group, —O—, —CO—, —S—, —SO ₂ —, —Se—, —NR ¹ —, —PR ¹ —, —P (O) R ¹ —, —BR ¹ — or —AlR ¹ —, wherein R ¹ represents a hydrogen atom, a halogen atom, a hydrocarbon group having 1 to 20 carbon atoms, or a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, May be different.

Examples of the metallocene catalyst include transition metal compounds represented by the following formula (II).
E ^{1 ′} E ^{2 ′} MX _q Y _r (II)
(In the formula, M, X, q, Y and r are the same as those in the formula (I). E ^{1 ′} and E ^{2 ′} are E ¹ and E ² in the formula (I) and are not crosslinked. .)

  Usually, a catalyst deactivator is added to the obtained polymerization liquid and stirred to deactivate the catalyst, and an oil phase (phase containing an olefin oligomer) and an aqueous phase containing a metal component derived from the catalyst (including a deactivator) Phase) is separated (decalcified).

  Examples of the quenching agent include alcohols, water, and aqueous solutions of acids, alkalis, oxygenated compounds, and the like, and specific examples include aqueous sodium hydroxide, ethanol, isopropyl alcohol, hydrochloric acid, and acetone.

Moreover, in this invention, the unreacted monomer C10 contained in a polymerization liquid is removed. At this time, light components such as trace moisture and solvent can be removed together. Such a light component removing step is usually performed under conditions of 220 to 250 ° C. and 3000 to 5000 PaA.
Unreacted C10 is, for example, 50 ppm or less in a weight ratio of C10 / C20.

  The polymerization solution that has undergone the above steps includes C20 +, for example, C20, C30, C40, and C50 +. In addition, a small amount of unreacted C10 may remain.

In the distillation step, C20 is separated from C20 + with a yield of 0.99 or more.
Usually, distillation is performed in a vacuum distillation column at a temperature below the boiling point of C20. This is because the boiling point of C20 at normal pressure is 335 ° C., but it exceeds the decomposition temperature (260 ° C.) of the polymerization product mixture. C20 is obtained from the top of the vacuum distillation column, and a by-product C30 + is obtained from the bottom of the column.

The yield of C20 at the top of the column is preferably 0.999 or more.
Since C20 exists in either the tower top or the tower bottom, the tower top yield of C20 can be calculated using C20 / C30 (weight ratio) in the tower bottom as an index. C20 / C30 varies depending on the ratio of C20 and C30 in the polymerization product, but according to a polymerization product composition such as a Schulz-Flory distribution by a general chain polymerization reaction, the production ratio of C20 and C30 is the same. Degree.
That is, the column top yield of C20 = 1-C20 / C30 (weight ratio at the column bottom). C20 / C30 (weight ratio) can be measured by gas chromatography.

  From the relationship of the mass balance, the more C20 mixed (residual) in the by-product C30 + at the bottom of the column, the lower the C20 yield at the top and the lower the productivity. In order to recover C20 at the column top with a yield of 0.99 or 0.999, C20 / C30 at the column bottom needs to be 0.01, preferably about 0.001.

  Table 1 shows tower bottom pressure and evaporation temperature (bubble point) for setting C20 / C30 at the tower bottom to 0.1, 0.01, 0.001, and 0.0.

  From Table 1, for example, when the column bottom pressure is 1 kPa-A, the yield of C20 can be set to 0.99 (C20 / C30 = 0.01) by setting the column bottom temperature to 258 ° C. .

In the distillation step, when the polymerization product is thermally decomposed at the bottom of the column, a volatile light component (VOC) having 6 to 16 carbon atoms generated by the decomposition is mixed into C20 at the top of the column.
Since this light component causes deterioration of product quality and affects the human body, the concentration in C20 is 100 ppm by weight or less, preferably 50 ppm by weight or less.
The concentration of light components in C20 can be measured by gas chromatography measurement.

Examples of the method for setting the light component concentration in C20 to 100 ppm by weight or less include a method in which the bottom temperature of the distillation column is 280 ° C. or less, preferably 260 ° C. or less, more preferably 250 ° C. or less.
When the tower bottom temperature is 280 ° C. or less, the residence time of the polymerization liquid at the tower bottom is preferably 15 to 20 minutes. When the tower bottom temperature is 260 ° C. or less, the residence of the polymerization liquid at the tower bottom The time is preferably 60 to 90 minutes.

In addition, the light component concentration in C20 was set as follows.
There is no legal restriction on the allowable concentration of VOC in the liquid, but the VOC indoor concentration guideline value in the gas is provided by the Ministry of Health, Labor and Welfare. This guideline value is 1 to several hundred μg / m ³ depending on the substance.

From this guideline value, the light component concentration in the liquid of the product C20, which is a gas generation source, was calculated based on the following concept. That is, C8 or C10 in the C20 liquid such that the vapor concentration of C8 or C10 which can be volatilized is several hundred μg / m ^{3 in} a state where the atmosphere 100 m ³ is sufficiently in contact with 1 kg of the product C20. The concentration of was calculated.
From the above, the light component concentration in the C20 liquid was set to 100 ppm by weight or less.

  From the above, in order to make the light component concentration in C20 100 ppm by weight or less, the bottom temperature of the distillation column is 280 ° C. or less, and in order to make the C20 yield 0.99 or more, The column bottom pressure is 2 kPa-A or less, preferably 1 kPa-A or less.

  The following (1) to (4) may be mentioned as a method for setting the bottom pressure of the distillation column to 2 kPa-A or less.

(1) Built-in condenser heat exchanger in distillation tower (Internal exchanger)
Providing it in the distillation column of the heat exchanger for condensation is preferable because pressure loss due to the gas linear velocity in the piping can be avoided.
In a general distillation column, the top of the column and the condenser outside the column are connected by piping, but pressure loss occurs due to the gas linear velocity in the piping. In particular, at a pressure around 1 kPa-A, the gas linear velocity increases, and the pressure loss increases accordingly. In order to avoid pressure loss, it is preferable to shorten the piping from the top of the column to the condenser, and the shortest time when the condenser is built in the distillation column.

(2) Installation of baffles at the bottom of the tower liquid pool When a baffle (liquid level control plate) is installed at the bottom of the liquid pool, the liquid at the reboiler outlet (liquid that has not evaporated) is brought into contact with the liquid in the tower. It is preferable because the temperature and pressure at the bottom of the column can be lowered.

(3) Adopting the bottom reboiler of the falling film evaporator (FFE) The falling film reboiler is a fixed tube plate type vertical heat exchanger, which is heated by a plurality of heated tubes. This is a reboiler which allows the liquid to be heated to flow in and evaporates by flowing down the heating wall surface into a film. In order to equalize the flow rate to each tube, a cylindrical ferrule is usually provided on all the tubes. The ferrule has a function as a weir, and the amount of inflow into each tube is made uniform by aligning the height of the weir.

In a commonly used natural circulation reboiler (thermo-siphon), since the liquid level exists in the heat exchanger, the pressure of the liquid's own weight is applied to the evaporation surface. Since this pressure is proportional to the liquid density and the liquid depth, it varies greatly depending on the location in the height direction of the longitudinal heat exchanger.
Further, even if the liquid at the lowest pressure position in the reboiler is evaporated, the gas-liquid mixed phase fluid needs to climb up the rising pipe connected to the distillation column main body together with the liquid, and the pressure rises due to the influence. For example, since the pressure rises to 1 kPa even at a liquid depth of about 10 cm, even if the pressure at the top of the column is reduced to 0.5 kPa-A, the total pressure at the bottom of the column can be easily reduced to a vacuum level of 1 kPa-A required for the process. The influence is so large that it exceeds.

The falling film membrane reboiler has no liquid depth, and there is no rising portion in the return pipe from the reboiler to the distillation column body. The liquid that has flowed into the tube flows down in a liquid film state on the wall surface of the tube, and the surface of the liquid film is connected to the distillation tower in a gas phase, so that a pressure increase due to the liquid depth does not occur.
In addition, since the falling liquid film type evaporator is not natural circulation but forced circulation, a pump is necessary.

(4) Countermeasures for air leakage A pump that draws out liquid such as C20 and C30 + is provided at the top and bottom of the tower. To connect this pump, a valve with low air leakage such as a bellows type valve should be used. preferable.

  Of the above (1) to (4), only one may be adopted, or two or more may be adopted. Preferably, (1) or (3) is adopted.

An example of a distillation column used in the first production method of the present invention is shown in FIG.
The distillation column main body 10 of the distillation column 1 is connected to a vacuum pump 20 via a vent condenser 22 at the top of the column, and a condenser 30 is provided inside the distillation column. A distillation packing 12 is provided in the center of the column.
A falling liquid film evaporation reboiler (falling liquid film reboiler) 40 is provided at the bottom of the tower via a pump 42, and a baffle 60 is provided in the liquid pool at the bottom of the tower. .

The polymerization liquid charged into the distillation tower 10 from the liquid disperser 52 is sent to the falling liquid film reboiler 40 by the pump 42 from the liquid pool at the bottom of the tower. The liquid to be heated is heated in the reboiler 40 and a part (mainly C20) becomes a gas, and is sent again into the distillation column 10. These gases liquefy when they reach the condenser 30 and are stored in a liquid pool at the top of the column. The stored liquid is drawn out by a pump 70 outside the tower, a part is collected, and a part is sent again from the liquid disperser 50 to the inside of the distillation tower 10.
The component (C30 +) that has not been vaporized in the reboiler 40 is sent again into the distillation column 10 as a liquid and is extracted from the bottom of the column.

Next, a vacuum distillation column generally used conventionally is shown in FIG.
The distillation column main body 110 of the distillation column 2 has a condenser 130 provided outside the distillation column via a pipe 132 at the top of the column. A vacuum pump 120 is connected to the condenser 130 via a vent system condenser 122. A tray-type gas-liquid contact means is provided at the center of the tower.
A natural circulation reboiler 140 is provided at the bottom of the tower.

As described above, when the condenser is provided outside the distillation tower, pressure loss occurs in the piping of the distillation tower and the condenser. Further, when a normal natural circulation reboiler is used as the reboiler, a pressure loss due to the liquid depth occurs.
This pressure loss is about 1 kPa or more in the piping, and about 1 kPa at a liquid depth of about 10 cm in the reboiler. That is, even if the pressure of a vacuum pump or the like disposed at the top of the tower satisfies 1 kPa-A (= 7.5 torr) or less, the tower bottom pressure is usually several times higher than 1 kPa-A due to the sum of these.

  Therefore, when a general distillation column is used, the column bottom temperature is preferably 260 ° C. or higher in order to recover the column top at 0.99 or higher. However, if the tower bottom temperature is too high, VOC generated by thermal decomposition may be mixed into the tower top product, which may deteriorate the product quality. On the other hand, if the tower bottom temperature is too low in order to prevent thermal decomposition, the product C20 may be lost to the tower bottom and the product yield may be reduced.

  Since C20 produced by the production method of the present invention has a reduced VOC content, it has little influence on the human body and does not deteriorate product quality.

Experimental example 1
[Pyrolysis experiment using continuous distillation tower]
A raw material (polymerization solution) containing 6 ppm by weight of C10 was distilled using a continuous distillation column in which a heat exchanger for condensation was incorporated and the bottom reboiler was a falling liquid film type.
Table 2 shows the composition of the raw materials.

  Distillation separation was performed at a liquid temperature in the tower bottom of 246 ° C. to 261 ° C., respectively. The column bottom pressure was adjusted by adjusting the feed rate of the raw material to the distillation column, the column top pressure and the reflux ratio.

  In addition, although the density | concentration of C10 in a raw material is 6 weight ppm, C10 in the isolate | separated C20 originating in this C10 will be about 18 weight ppm. This is because when C20 contained in the raw material at 29.6% by weight is separated at the top of the column with a yield of about 1, C30 + is removed, but C10 is recovered together with C20 and C10 is concentrated.

The concentration of light components (components of C7 to 16) contained in the distillation column top fraction was analyzed by gas chromatography under the following conditions. Moreover, the ratio of C20 / C30 at the tower bottom was measured by gas chromatography. The results are shown in Table 3.
In addition, although the density | concentration of the light part C6 is not measured, C6 produced by decomposition | disassembly is very trace amount, and is 0-5 weight ppm normally.
In addition, the density | concentration of a light part is the value which deducted 18 weight ppm (light part derived from C10 in a raw material) from the analytical value of a light part.

[Gas chromatography measurement conditions]
Column: DB-5MS (30 m × 0.53 mm × 1.0 μm)
Carrier gas flow rate: 40 cm / second Injection mode: Cool on-column injection injection, detection temperature: 320 ° C.
Column temperature: 50 ° C. (0.1 minute hold), temperature rise at 10 ° C./min, 300 ° C. (25 min hold)
Injection volume: 1.0 μL

[Experimental considerations]
From Table 3, it can be seen that the VOC component significantly increases due to decomposition as the bottom temperature of the distillation column rises.
Further, as described above, since the concentration of light components in the C20 liquid is preferably 100 ppm by weight or less, the distillation column is operated so that the maximum temperature at the bottom of the column is about 260 ° C., preferably 258 ° C. or less. It can be said that it is preferable.

The residence time at the tower bottom of the experimental machine was 0.8 to 1.2 hours, which was about 1 hour.
In addition, if the residence time of the raw material is shortened, the decomposition amount becomes small.
From Table 3, it can be seen that when the temperature is increased by 10 ° C., the light component concentration is increased about twice. That is, when the temperature rises by 10 ° C., the decomposition rate increases about twice. Therefore, even at a high tower bottom temperature, thermal decomposition can be suppressed by shortening the residence time.

  By changing the equipment such as reducing the diameter of the tower bottom, the equivalent C20 yield can be secured even if the residence time is shortened to about 15 minutes (about 1/4 residence time). Furthermore, even if the temperature is about 20 ° C., the light component concentration in the C20 solution is considered to be about the same as above.

Experimental example 2
Consider pressure loss and temperature rise in a distillation column that is not a distillation column with a condenser at the top of the column, but a condenser that is externally connected and the distillation column itself and the condenser are connected by piping. did.
That is, the simulation calculation is performed under the following conditions, and the case where the condenser is an interior type and the case where the condenser is an exterior type and the size (diameter) of the connection pipe to the distillation column is 20, 16, 12 inches. The pressure loss and temperature increase were determined. The results are shown in Table 4.

As calculation conditions, the composition of the raw material supplied to the distillation column is as follows: C20 40% by weight, C30 30% by weight, C40 20% by weight, C50 10% by weight, raw material supply rate 2500 kg / hr, The C20 / C30 concentration was 0.003 or less and the reflux ratio R / D = 1.0.
Further, the upper theoretical plate number 2 and the lower theoretical plate number 2 were separated by regular packing, and each packing had a diameter of 1.6 m and a height of 1 m. The regular packing was a low differential pressure type 252Y manufactured by Sulzer.

  The column top fraction was C20, and the flow rate was about 1000 kg / hr, but when the reflux ratio R / D = 1.0, the column top evaporation gas amount was about 2000 kg / hr.

From Table 4, it can be seen that when the condenser is an exterior, the rise in the tower bottom pressure due to pressure loss is remarkable, and the tower bottom temperature exceeds the target value of 260 ° C. or the limit value of 280 ° C. The pressure loss rise due to the piping to the condenser is about 1 kPa, and the tower temperature rise accompanying this is 30 ° C. or more.
From the above, it is preferable that the condenser is an internal type.

  The olefin polymer having 20 carbon atoms produced by the production method of the present invention can be used for a thickener, a plasticizer, a diluent, a lubricating oil, a solvent, a synthetic intermediate raw material, and the like.

DESCRIPTION OF SYMBOLS 1, 2 Distillation tower 10,110 Distillation tower main body 12 Distillation packing 20,120 Vacuum pump 22,122 Vent condenser 30,130 Condenser 40 Falling liquid film reboiler 42,70,170 Pump 50,52 Liquid Disperser 60 Baffle 140 Natural circulation reboiler

Claims (6)

  A polymer solution containing a polymer having 20 or more carbon atoms is produced by polymerizing an α-olefin having 10 carbon atoms, and after removing the unreacted α-olefin having 10 carbon atoms from the polymer solution, the polymer solution is distilled. Then, a method for producing a olefin polymer having 20 carbon atoms, comprising separating a olefin polymer having 20 to 16 carbon atoms having a carbon content of 6 to 16 having a carbon content of 100 wt ppm or less in a yield of 0.99 or more. .   The method for producing an olefin polymer having 20 carbon atoms according to claim 1, wherein the distillation is performed at 280 ° C or lower.   The method for producing an olefin polymer having 20 carbon atoms according to claim 1 or 2, wherein the distillation is performed in a distillation column equipped with a falling liquid film evaporator.   The method for producing an olefin polymer having 20 carbon atoms according to any one of claims 1 to 3, wherein the distillation is performed in a distillation column provided with a tower top condenser of a distillation column internal heat exchanger type.   The method for producing an olefin polymer having 20 carbon atoms according to any one of claims 1 to 4, wherein the polymerization is performed in the presence of a metallocene catalyst.   The olefin polymer of carbon number 20 obtained by the manufacturing method in any one of Claims 1-5.