JP2002145908A - Method for producing ethylene-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polymer balanced in solid characteristics and melt flowability at high level in the usage of a blow molding by highly maintaining the productivity per polymerization vessel. SOLUTION: In producing an ethylene-based polymer by using two polymerization vessels connected in series in the presence of a highly active Ziegler's catalyst, the whole produced polymer is brought to have 2.0-3.5 dL/g intrinsic viscosity [η]w and, by controlling the temperature and the pressure of at least one of pressure reducing tanks connected to the two polymerization vessels in conditions of 50-80 deg.C and 30-100 KpaG pressure respectively, the polymer obtained in the pressure reducing tank having 7-15 dL/g intrinsic viscosity [η]f is brought to be included in 0.5-10 wt.% in the whole polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a novel ethylene polymer. More specifically, the present invention relates to a method for producing an ethylene polymer, which provides a polymer having a smooth surface state (skin) of a molded product in blow molding, particularly in large blow molding for molding a container of 50 L or more. .

[0002]

2. Description of the Related Art In the field of blow molding, which is one of the main uses of ethylene-based polymers, it is important to use ethylene-based polymers having excellent properties in both solid physical properties and melt flow properties. Solid physical properties include mechanical strength such as rigidity and impact resistance, and environmental strength such as environmental stress crack resistance (ESCR). In addition, it is required that the melt has no sagging (drawdown) during blow molding, has a uniform thickness, and has smooth inner and outer surfaces. In this type of polymer, the solid state properties are improved when the molecular weight is increased, but the surface state is deteriorated due to a decrease in fluidity. Conversely, lowering the molecular weight improves the flowability and improves the surface condition,
Solid physical properties decrease. In order to obtain a polymer having such contradictory properties, a technique of increasing the molecular weight relatively to improve the solid physical properties and broadening the molecular weight distribution to secure fluidity has been adopted.

For example, an ethylene polymer using a Phillips type catalyst which gives a polymer having a relatively wide molecular weight distribution has an improved melt fluidity and has no drawdown.
A molded body having good skin can be obtained. However,
Since both the increase in molecular weight and the expansion of molecular weight distribution are still insufficient, in terms of solid physical properties such as low ESCR,
Still has drawbacks.

On the other hand, an ethylene polymer obtained with a Ziegler-type catalyst generally has a narrow molecular weight distribution and is not suitable for use in blow molding. In order to improve this point, a method of producing polymers having different molecular weights in a plurality of polymerization steps using a Ziegler-type catalyst and mixing them to produce a polymer having a wide molecular weight distribution as a whole may be considered. It has been proposed as a polymerization method.

[0005] For example, in Japanese Patent No. 2712307, the molecular weight and production ratio of each component obtained in three or more polymerization reactors are determined by limiting viscosity [η] w which is the molecular weight of an ethylene polymer finally produced. And the α-olefin content of each component is determined based on the ratio of each component, thereby improving the viscoelastic properties to obtain an ethylene polymer having high compatibility with blow molding and extrusion molding. It can be manufactured. However, the ethylene-based polymer having a wide molecular weight distribution obtained by using three polymerization reactors has a high molecular weight finally produced by containing a large amount of low molecular weight components that reduce mechanical strength. However, for a container of 50 L or more, especially a plastic drum of 100 L or more, the impact strength required for the resin itself cannot be satisfied, and it is necessary to increase the thickness of the container and maintain the strength by weight, Not preferred. Furthermore, for drum applications used to store high-purity chemicals, low molecular weight components that increase by broadening the molecular weight distribution are relatively easy to elute from the polymer into the filling solution, so they elute into the filling solution. The resulting fine particles cannot be reduced to a low level, which is not preferable.

Further, Japanese Patent Publication No. 6-99510, Japanese Patent Publication No. 6-99511 and Japanese Patent Publication No. 6-55912 disclose a multi-stage continuous polymerization process using a polymerization apparatus having at least three polymerization units. In a continuous olefin polymerization method for producing polyolefins having different intrinsic viscosities [η] in respective polymerization vessels, in at least one of the multi-stage polymerization steps, 0% of the raw olefin to be polymerized in the entire polymerization step is used. 0.1-5% by weight at 30 ° C
Polymerization at a temperature of less than 15 dL
A continuous polymerization method for olefins, characterized in that an ultrahigh molecular weight polyolefin of at least / g is produced. In these methods, the melt tension and melt elasticity can be improved by expanding the molecular weight distribution, and drawdown can be prevented. However, since an ultra-high molecular weight product having an intrinsic viscosity [η] of 15 dL / g or more is produced, it is easy to produce bumps and gels in the polymer, and it is difficult to obtain a good molded product surface state (skin). . Further, the use of three or more polymerization reactors is not preferable in terms of an increase in complexity of the reaction operation and a decrease in productivity per polymerization reactor.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems by using only two polymerization reactors while maintaining high productivity per polymerization reactor without impairing the operability of the reaction. Another object of the present invention is to provide a method for producing a polymer in which the solid properties and the melt fluidity are balanced at a high level in blow molding applications.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, using two polymerizers connected in series, each polymerizer has a different molecular weight. In the method for producing a coalescence, by setting the conditions of the depressurization tank connected to the polymerization vessel to a specific range, a polymer having a specific molecular weight can be produced in a specific ratio in the tank, and has excellent solid physical properties and excellent blown properties. It has been found that the skin of the molded article is good, and the present invention has been completed.

That is, the present invention relates to a method for producing ethylene or ethylene and having 3 to 2 carbon atoms in the presence of a highly active Ziegler type catalyst.
In a method for producing polymers having different molecular weights in each polymerization vessel using two polymerization vessels in which 0 α-olefins are connected in series, the intrinsic viscosity [η] of all the resulting polymers is obtained.
w is 2.0 to 3.5 dL / g, and the temperature of at least one of the depressurization tanks connected to the two polymerization reactors is 50
By adjusting the pressure at ~ 80 ° C and the pressure at 30-100 KPaG, the intrinsic viscosity [η] obtained in the depressurization tank is obtained.
A method for producing an ethylene-based polymer, characterized in that a polymer having f of 7 to 15 dL / g is contained in an amount of 0.5 to 10% by weight based on the whole polymer.

The ethylene polymer according to the present invention is an ethylene homopolymer, or ethylene and α-α having 3 to 20 carbon atoms.
It is an ethylene copolymer composed of olefin. Carbon number 3
Examples of the α-olefin of -20 to -20 include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-eicosene and 4-methyl-1
-Pentene and the like.

As the highly active Ziegler type catalyst, Mg,
Examples of the catalyst include a solid catalyst component (A) containing Ti and halogen as essential components and a catalyst containing an organic aluminum compound (B) as main components. Specific examples of the solid catalyst component (A) include JP-A-50-51587 and JP-A-56-155205.
JP-A-60-262802, JP-A-4-262802
The catalyst components described in JP-A-309505 and JP-A-7-41513 are exemplified.

More specifically, it is preferable to use a solid catalyst component obtained by adding an aluminum halide to a homogeneous solution containing at least a reaction product of metal magnesium and alcohol and alkoxytitanium. Here, the homogeneous solution is a magnesium component, an alcohol component,
It refers to a titanium component dissolved in a solution in a homogeneous state. If precipitates or suspended matters are present, only a heterogeneous catalyst can be obtained even when reacted with aluminum halide,
The object of the present invention is not to obtain an ethylene copolymer having good fluidity (skin). The amounts used for preparing the solid catalyst components are selected such that the atomic ratio of magnesium to titanium is in the range of 1: 0.05 to 0.5, and the atomic ratio of magnesium to aluminum is in the range of 1: 2 to 20. Is preferred. When the atomic ratio of magnesium: titanium is small outside the above range, it is difficult to obtain a uniform solution. Conversely, if it is large, a large amount of titanium will be contained in the ethylene-based polymer, causing the polymer to be colored or discolored, or the content of titanium to be eluted from the blow-molded container to the contents. The quality of the product is deteriorated, which is not preferable. When the atomic ratio of magnesium: aluminum is small outside the above range, the catalytic activity becomes insufficient, the molecular weight distribution of the obtained polymer is narrow, and the fluidity is poor. Conversely, if it is large, the molecular weight distribution and composition distribution will be too wide, a polymer with a very low molecular weight will be generated during polymerization, stability to heat and oxygen will be reduced, and various additives will be indispensable, Short chain branches generated by copolymerization of ethylene and α-olefin are unevenly distributed in the polymer, and the effect of improving ESCR cannot be expected.

As the organoaluminum compound (B),
A straight or branched chain carbon number 1 usually used in the art.
Aluminum compounds having up to 20 alkyl groups are used. Specific examples include trimethylaluminum, triethylaluminum, tri-i-butylaluminum, tri-n-butylaluminum, isoprenylaluminum, tri-n-hexylaluminum, diethylaluminum chloride and the like.

In the present invention, the polymerization reaction is carried out using two polymerization units connected in series. Both polymerization reactors are filled with an inert solvent, and under a condition where the solvent is continuously supplied and kept at a constant pressure, together with ethylene and α-olefin having 3 to 20 carbon atoms as raw materials, Hydrogen, which is effective and easy to handle as a regulator, is continuously supplied, and the polymerization is carried out at a constant temperature. The catalyst is
It is continuously supplied only to the first polymerization reactor, and is supplied to the second polymerization reactor as a slurry containing the polymer generated in the first polymerization reactor.

[0015] The polymerization reaction is carried out under the following conditions. That is, a polymerization temperature of 20 to 110 ° C. and a polymerization pressure of 150 to 10
2,000 KPaG, 3 to 20 as an inert solvent.
Alkanes or cycloalkanes having carbon atoms,
For example, propane, isobutane, pentane, hexane,
Cyclohexane and the like are used.

As for the polymerization conditions, different hydrogen concentrations and α-olefin concentrations, and further, reaction temperatures are selected in both the polymerization reactors. The molecular weight of the produced polymer is adjusted by adjusting the hydrogen concentration in the polymerization vessel to an appropriate amount.

In the present invention, the intrinsic viscosity of the polymer produced in the polymerization vessel is [η] r, the production ratio is r%, and the intrinsic viscosity of the polymer in each polymerization vessel and the production ratio to the total polymer are as follows:
The first polymerization vessel is represented by [η] r1, r1%, and the second polymerization vessel is represented by [η] r2, r2%. Similarly, the intrinsic viscosity of the polymer generated in each depressurization tank row is [η] f, the generation ratio is f%, and the intrinsic viscosity of each depressurization tank row and the generation ratio for all polymers are respectively One depressurization tank row is [η] f
1, f1%, and the second depressurization tank row are represented as [η] f2, f2%. The intrinsic viscosity [η] w of the polymer finally obtained from the above is obtained as the sum of the intrinsic viscosity of the polymer produced in each apparatus multiplied by the production ratio, and is expressed by the following equation.

[Η] w = ([η] r1 × r1% + [η]
f1 × f1% + [η] r2 × r2% + [η] f2 × f2
%) / 100 100% = r1% + f1% + r2% + f2% The limiting viscosity and the production ratio of the polymer produced in each polymerization vessel are, for example, low molecular weight component in the first polymerization vessel, high molecular weight in the second polymerization vessel. When the components are polymerized, the intrinsic viscosity [η] r of the low molecular weight component is 0.6 to 2.4 dL / g, preferably 0.9 dL / g.
２．１2.1 dL / g, and the production ratio is 20:80 to 80:20 in terms of the production ratio of low molecular weight components: the production ratio of high molecular weight components.
Preferably, it is desirable to manufacture at 40:60 to 60:40. At this time, the intrinsic viscosity [η] r of the high molecular weight component polymerized in the second polymerization vessel becomes 3.2 to 5.0 dL / g. When the intrinsic viscosity of the low molecular weight component is larger than the above range,
The flow of the molten resin during molding is poor, the skin of the molded body is deteriorated, and the molding cycle is undesirably long. Also,
If the intrinsic viscosity of the low molecular weight component is smaller than the above range, the mechanical strength such as impact resistance is reduced, which is not preferable.

When the high molecular weight component is polymerized in the first polymerization reactor and the low molecular weight component is polymerized in the second polymerization reactor, the intrinsic viscosity [η] r of the high molecular weight component is 3.0 to 6.0 dL / g, preferably 3 to 6.0 dL / g. .
2 to 5.0 dL / g, and the production ratio is 20:80 to 80:
It is desirable to manufacture at 20, preferably 40:60 to 60:40. When [η] r is smaller than the above range, mechanical strength such as impact resistance is reduced, and when [η] r is larger than the above range, the flow of the molten resin during molding is poor and the skin of the molded article is poor. Or the molding cycle becomes longer, which is not preferable.

If the production ratio of the low molecular weight component is smaller than the above range, the fusion strength of the pinch-off portion of the blow-molded article becomes weak, and the molded product is easily broken from the pinch-off portion by impact due to dropping, which is not preferable. Also,
When the production ratio of the low molecular weight component is larger than the above range, the flow of the molten resin during molding is poor, and the skin of the molded body is unfavorably deteriorated.

The slurry containing the polymer discharged from the first polymerization vessel is continuously supplied to a device called a depressurization tank directly connected to the polymerization vessel. Here, it is necessary to depressurize and remove the unreacted monomer and hydrogen present in the slurry before supplying them to the second polymerization reactor or the post-treatment step for connecting. Similarly, the slurry containing the polymer discharged from the second polymerization vessel is continuously supplied to a device called a depressurization tank directly connected to the polymerization vessel. Also here, it is necessary to depressurize and remove the unreacted monomer and hydrogen present in the slurry before supplying them to the post-treatment step for connecting.

The α-olefin having 3 to 20 carbon atoms may be supplied to a polymerizer for producing a polymer having a high molecular weight component in order to improve environmental stress cracking resistance (ESCR) required as solid physical properties. It is suitable. Such a comonomer would be added to a polymerization vessel operating at a low hydrogen concentration.

Further, as another case, a polymerizer for obtaining a polymer having a relatively low molecular weight may be operated at a high concentration of hydrogen.

Contrary to the above conditions, if the slurry discharged from the first polymerization reactor is sent to the second polymerization reactor without depressurizing and removing the unreacted monomer, the slurry is brought into the second polymerization reactor. The composition in the second polymerization vessel cannot be controlled to a desired one due to the excess monomer.

Further, when controlling the physical properties of the polymer by estimating the amount of monomer present in the polymerization vessel, depressurization is also performed in measuring the composition of the unreacted gas in the depressurized polymerization vessel. There is a need.

The depressurizing tank main body has a stirrer for the purpose of preventing sedimentation of the polymer in the slurry and facilitating depressurizing.
Further, a circulation line and a pump for circulating the slurry containing the polymer are provided. Also, at least one unit is connected in series to the polymerization vessel as a depressurizing tank, and two or more units can be connected in series or in parallel to be used as a tank line.

It is also possible to improve the degassing efficiency by changing the setting of temperature, pressure and average residence time as the operating conditions of the depressurizing tank, and connecting a plurality of depressurizing tanks in series. By sequentially setting the pressure lower, the pressure can be easily released.

As described above, in the present invention, the depressurization tank, which is an apparatus originally intended for removing unreacted gas, is provided by setting the conditions of the depressurization tank to a specific range.
It aims to improve the skin of a molded product by obtaining a polymer of a desired molecular weight and ratio at a predetermined residence time while achieving a target depressurization without supplying raw materials as in a polymerization vessel. It is. The desired polymer can be obtained in at least one depressurization tank row attached to each polymerization vessel, and is supplied to a second polymerization vessel having different reaction conditions from the first depressurization tank row attached to the first polymerization vessel. It can be obtained in the accompanying second depressurization tank row. The obtained polymer is [η] f1 or [η]
f [eta] f is 7 to 15 dL / g, preferably 10 to 13 dL / g, and 0.5 to 10% by weight, preferably 0.5 to 10% by weight, based on the whole polymer to be polymerized in the entire polymerization step. 1.0-5% by weight at a temperature of 50-80 ° C and a pressure of 30-1
It is obtained under 00 KPaG. At this time, the total average residence time of the depressurization tank line accompanying each polymerization step for obtaining a polymer is 0.3 to 1.5 hr.
When [η] f or the amount of the component is smaller than the above range, no improvement in skin is observed, and when [η] f or the amount of the component is too large, the appearance is inferior such as a gel or butter due to an ultrahigh molecular weight component. Is not preferred.

The ethylene polymer according to the present invention is required to have a molecular weight in the range of intrinsic viscosity [η] w of 2.0 to 3.5 dL / g. If it is smaller than this range, the solid properties are insufficient and the impact strength is small, and if it is large, the melt fluidity is poor and only a blow molded article having no smooth skin can be obtained.

In the present invention, the temperature of at least one of the depressurization tanks connected to the two polymerization reactors is 50 to 8
By adjusting the pressure at 0 ° C. and the pressure at 30 to 100 KPaG, a polymer having an intrinsic viscosity [η] f of 7 to 15 dL / g is contained in an amount of 0.5 to 10% by weight based on the whole polymer. Must be. Satisfying these conditions produces a polymer that balances solid properties and melt fluidity at a high level in blow molding applications while maintaining high productivity per polymerization unit using only two polymerization units. Important above. The reason is not clear,
When the temperature is out of the above range and the pressure is low, the component having the intrinsic viscosity [η] f of 7 to 15 dL / g is not homogeneously dispersed in the ethylene polymer, and becomes a gel. Conversely, if the temperature is outside the above range or the pressure is high, it is difficult to obtain a component having an intrinsic viscosity [η] f of 7 to 15 dL / g, and satisfy solid physical properties such as strength. Can not be done.

[0031]

As is apparent from the above description, according to the present invention, (1) using only two polymerization reactors, the productivity per polymerization reactor is maintained at a high level without impairing the operability of the reaction. While producing a polymer that balances solid physical properties and melt fluidity at a high level in blow molding applications,
(2) When the ethylene-based polymer obtained by the present invention is used for blow molding, a container having smooth inner and outer surfaces can be obtained, and (3) good stability against heat and the like during molding. Therefore, it is not essential to add a heat stabilizer or an antioxidant as an additive. (4) The blow-molded container contains only a trace amount of a titanium component or the like in a polymer serving as the container itself, and Since it is possible not to include additives etc.,
These components do not elute into the contents of the container,
It does not deteriorate the quality or purity of the contents.

[0032]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Various physical property tests in Examples and Comparative Examples were performed by the following methods.

(1) Melt flow rate The melt flow rates (MFR and HLMFR) under 2.16 kg and 21.6 kg loads are determined according to JIS K-
The measurement was performed according to the conditions 4 and 7 of 7210 (1995).

(2) Intrinsic Viscosity Capillary Viscosity Automatic Measurement System SS-2 from Shibayama Chemical Instruments Co., Ltd.
The measurement was carried out in orthodichlorobenzene at 135 ° C. with 01H-2T.

(3) Evaluation of Skin The good melt fluidity, one of the effects of the present invention, was confirmed by actually molding a container of 50 L or more by blow molding and observing the skin on the inner and outer surfaces. Molding of a 100 L closed type plastic drum with the obtained polymer was performed using a NB80 / P115 type hollow molding machine manufactured by Nippon Steel Works at 200 to 230 ° C. at an injection pressure of 0.6 MPaG and a blow time of 120 sec. The skin was visually checked.

Further, since the skin is greatly affected by the flow of the molten polymer and the change in the state of stoppage, it was also confirmed by a method using a capillograph. The ethylene-based polymer pellets were filled at a temperature of 190 ° C. and the barrel of the capillary rheometer PMD-C manufactured by Toyo Seiki Seisakusho with the die removed was filled with 15 g, extruded once at 200 mm / min, and then extruded at 0 mm / min. After standing for 1 minute, the condition of the skin appearing on the extruded product immediately after being extruded at an extrusion speed of 500 mm / min was observed.

(4) ESCR Measured in accordance with the measuring method of “constant strain environmental stress crack test” of JIS K-6760 (1981).

(5) Flexural stiffness The flexural stiffness was measured in accordance with the measuring method of "Plastic flexural stiffness test by cantilever beam" in JIS K-7106 (1995).

(6) Charpy impact value Measured according to the measuring method of "Charpy impact strength test" of JIS K-7111 (1996).

Example 1 (1) Preparation of solid catalyst component (A) In a 10 L stainless steel autoclave equipped with a stirrer, 108.2 g (1.80 mol) of i-propanol and 134.6 g (1) of n-butanol were added. .82 mol), 2.0 g of iodine and 40 metallic magnesium powder
g (1.65 mol) and titanium tetrabutoxide 2
After adding 24.1 g (0.66 mol) and further adding 2.0 L of hexane, the temperature was raised to 80 ° C., and the mixture was stirred for 1 hour under a blanket of nitrogen while excluding hydrogen gas generated. Subsequently, the temperature was raised to 120 ° C., and the reaction was carried out for 1 hour to obtain a homogeneous solution containing Mg and Ti. Set the internal temperature of the autoclave to 4
Keep at 5 ° C, 30% of diethylaluminum chloride
1.32 kg (3.3 mol) of a hexane solution was added over 1 hour. After adding all, the mixture was stirred at 60 ° C. for 1 hour. Next, 197.0 g (3.3 g atom of silicon) of methylhydropolysiloxane (viscosity of 30 centistokes at 25 ° C.) was added, and the mixture was reacted under reflux for 1 hour. After cooling to 45 ° C., 2.81 kg (9.1 mol) of a 50% hexane solution of i-butylaluminum dichloride.
Was added over 2 hours. After adding all, at 70 ° C 1
The mixture was stirred for an hour to obtain a solid catalyst component (A) having a Ti content of 11 wt%. The obtained solid catalyst component (A) was used for the next polymerization step as a hexane slurry after removing remaining unreacted substances and by-products using hexane.

(2) Polymerization In a first polymerization vessel having an inner volume of 370 L, 183 L / hr of dehydrated and purified hexane, 18 mmol / hr of tri-i-butylaluminum as an organoaluminum compound (B),
While continuously supplying the solid catalyst component (A) at a rate of 0.79 g / hr and discharging the polymerization content at a required rate,
At 85 ° C., ethylene was supplied at a rate of 20.3 kg / hr, the ethylene concentration was maintained at 1.56 wt%, hydrogen was maintained at an ethylene concentration ratio of 0.269 mol / mol, and the total pressure was 2.9.
The first-stage polymerization was continuously performed in a liquid-full state under the conditions of MPaG and an average residence time of 1.8 hr. The slurry containing the polymer sampled directly from the first polymerization vessel was filtered, and the [η] r1 of the powder obtained after drying was 0.89.
dL / g. The hexane slurry containing the polymer obtained in the first polymerization vessel was pressure 59 KPaG, temperature 70 ° C,
It was continuously sent to one depressurization tank with an average residence time of 0.6 hr to flush unreacted hydrogen and ethylene (the MFR of the polymer in the first stage was 14.6 g / 10 m
in, [η] f1 is 0.92 dL / g). Thereafter, the hexane slurry containing the polymer was introduced into a second polymerization vessel having an internal volume of 545 L, and the solid catalyst component and alkylaluminum were not added, but fed at a rate of 113 L / hr, and the contents of the polymerization vessel were discharged at a required speed. At a temperature of 80 ° C., ethylene was supplied at a rate of 20.7 kg / hr, and an ethylene concentration of 0.75 wt% and a hydrogen to ethylene concentration ratio of 0.033
mol / mol, the second-stage polymerization was carried out under the conditions of a total pressure of 2.0 MPaG and an average residence time of 1.6 hr. The slurry containing the polymer sampled directly from the second polymerization vessel was filtered, the HLMFR of the powder obtained after drying was 11.3 g / 10 min, and the [η] r2 was 2.11 dL /
g. The slurry from the second polymerization vessel was subjected to a separation and drying process after flushing unreacted hydrogen and ethylene at a pressure of 59 KPaG, a temperature of 70 ° C. and an average residence time of 1.0 hr in one depressurization tank. , HLMFR is 9.8g
/ 10 min, [η] w (the intrinsic viscosity of the final polymer) was 2.24 dL / g, and a polymer powder having a Ti content of 1.9 ppm was obtained.

The resulting polymer powder was pelletized at 230 ° C. without adding any additives. The obtained ethylene polymer pellets were HLMFR 8.9 g / 10 min, ES
The CR was 160 hr, the stiffness was 850 MPa, and the Charpy impact value was 27 kJ / m ² .

(3) Evaluation of Molded Surface Using the above-mentioned ethylene polymer pellets, a 100 L closed type plastic drum was molded at a predetermined temperature, injection pressure and blow time to obtain a molded product. A drop strength test was performed on the obtained drum molded product. The drum is filled with 90% of a 50% aqueous solution of ethylene glycol, and 1.9
From the height of m, the torso was dropped horizontally, and it was confirmed that there was no damage. Further, a sample was obtained by barrel extrusion under predetermined conditions using a capillary rheometer. The skin of the drum molded product and the barrel extruded product were all good, and no melt fracture or shark skin was observed.

Example 2 (1) Polymerization In a first polymerization vessel having an inner volume of 370 L, 414 L / hr of dehydrated and purified hexane and 107 mmol / h of tri-i-butylaluminum as an organoaluminum compound (B) were used.
r, the solid catalyst component (A) was continuously supplied at a rate of 1.51 g / hr, and ethylene was supplied at 85 ° C. at a rate of 20.5 kg / hr while discharging the polymerization content at a required rate. , Ethylene concentration 0.62 wt%, hydrogen to ethylene concentration ratio 0.12 mol / mol, total pressure 2.
Under the conditions of 9 MPaG and an average residence time of 0.84 hr,
The first-stage polymerization was continuously performed in a full state. The slurry containing the polymer sampled directly from the first polymerization vessel was filtered, and [η] r1 of the powder obtained after drying was 2.
It was 13 dL / g. The hexane slurry containing the polymer obtained in the first polymerization vessel was pressure 59 KPaG, temperature 70
° C and an average residence time of 0.3 hr, continuously sent to one depressurization tank to flush unreacted hydrogen and ethylene (the MFR of the polymer in the first stage was 0.22 g / 10
min, [η] f1 is 2.19 dL / g). Thereafter, the mixture was introduced into a second polymerization vessel having an internal volume of 545 L, and the solid catalyst component and alkylaluminum were not added.
/ Hr, and while discharging the contents of the polymerization vessel at a required rate, ethylene is supplied at 80 ° C. at a rate of 23 kg / hr, and an ethylene concentration of 0.92 wt% and a hydrogen to ethylene concentration ratio of 0.034 mol / mol. And total pressure 2.0
The second stage polymerization was carried out under the conditions of MPaG and an average residence time of 0.63 hr. The slurry containing the polymer sampled directly from the second polymerization vessel was filtered, and the HLMFR of the powder obtained after drying was 2.79 g / 10 min, [η].
r2 was 2.79 dL / g. The slurry from the second polymerization vessel was subjected to a pressure of 59 KPaG and a temperature of 7 in one decompression tank.
At 0 ° C. and an average residence time of 0.4 hr, unreacted hydrogen and ethylene were flushed, and then separated and dried.
LMFR 2.24 g / 10 min, [η] w 2.9
A polymer powder having 6 dL / g and a Ti content of 3.0 ppm was obtained.

With respect to 100 parts by weight of the obtained polymer powder,
0.1 parts by weight of Irganox 1010 (trade name, manufactured by Ciba Geigy) as a phenolic stabilizer, 0.1 parts by weight of Irgafos 168 (trade name, manufactured by Ciba-Geigy) as a phenolic stabilizer, DSTP (trade name) Name, manufactured by Yoshitomi Pharmaceutical Co., Ltd.), 0.07 parts by weight of calcium stearate, 0.15 parts by weight, and α, α′- as an organic peroxide.
Bis (t-butylperoxy) diisopropylbenzene was added in an amount of 0.01 part by weight and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet was 2.09 g / 10 min.

(2) Evaluation of Molded Surface The above-mentioned ethylene polymer pellets were evaluated in the same manner as in Example 1. The skin of the obtained drum molded product and barrel extruded product was good, and no melt fracture or shark skin was observed.

Example 3 (1) Polymerization In a first polymerization vessel having an internal volume of 37 m ³ , dehydrated and purified hexane 10.4 m ³ / hr, and tri-i-butylaluminum as an organoaluminum compound (B) 1.8 mol / hr. h
r, The solid catalyst component (A) is continuously supplied at a rate of 0.16 kg / hr, and ethylene is supplied at 85 ° C. at a rate of 7.7 t / hr while discharging the polymerization content at a required rate. , Ethylene concentration 0.46 wt%, hydrogen to ethylene concentration ratio 0.26 mol / mol, total pressure 2.7
Under the conditions of MPaG and an average residence time of 1.72 hr, the first-stage polymerization was continuously performed in a liquid full state. The slurry containing the polymer sampled directly from the first polymerization vessel was filtered, and [η] r1 of the powder obtained after drying was 1.8.
It was 3 dL / g. The hexane slurry containing the polymer obtained in the first polymerization vessel was subjected to a pressure of 59 KPaG and a temperature of 65 KPaG.
Unreacted hydrogen and ethylene were flushed in a single depressurization tank at 1.4 ° C. and an average residence time of 1.4 hr (the MFR of the polymer in the first stage was 0.96 g / 10 min, [η]
f1 is 1.88 dL / g). After that, the internal volume 54.5m
³ , the solid catalyst component and alkylaluminum were not added, and hexane was supplied at 4.7 m ³ / hr, and the content of the polymerization reactor was discharged at a required speed.
At a rate of 3.86 t / hr, maintaining an ethylene concentration of 1.62 wt% and a hydrogen to ethylene concentration ratio of 0.018 mol / mol at a total pressure of 2.0 MPa.
The second-stage polymerization was performed under the conditions of aG and an average residence time of 1.63 hr. The slurry containing the polymer sampled directly from the second polymerization vessel was filtered, and the HLMFR of the powder obtained after drying was 3.39 g / 10 min, [η].
r2 was 2.66 dL / g. The unreacted hydrogen and ethylene were flushed from the slurry from the second polymerization vessel at a pressure of 59 KPaG, a temperature of 62 ° C. and an average residence time of 0.1 hr in one auxiliary depressurization tank. Subsequently, the pressure was set to 49 KPa in one depressurization tank connected in series.
G, at a temperature of 57 ° C. and an average residence time of 0.4 hr, after flushing unreacted hydrogen and ethylene, passing through a separation and drying step to obtain an HLMFR of 2.86 g / 10 min.
A polymer powder having [η] w of 2.82 dL / g and a Ti content of 1.1 ppm was obtained.

As in Example 1, 23
Pelleted at 0 ° C. The HLMFR of the obtained ethylene polymer pellet was 2.51 g / 10 min.

(2) Evaluation of Molded Surface The same evaluation as in Example 1 was performed using the above-mentioned ethylene polymer pellets. The skin of the obtained drum molded product and barrel extruded product was good, and no melt fracture or shark skin was observed.

Example 4 (1) Polymerization In a first polymerization vessel having an inner volume of 370 L, 150 L / hr of dehydrated and purified hexane, 18 mmol / hr of tri-i-butylaluminum as an organoaluminum compound (B),
While continuously supplying the solid catalyst component (A) at a rate of 0.63 g / hr and discharging the polymerization content at a required rate,
At 80 ° C., ethylene was supplied at a rate of 20.0 kg / hr, the ethylene concentration was maintained at 0.71 wt%, hydrogen was maintained at an ethylene concentration ratio of 0.051 mol / mol, and the total pressure was 2.9.
The first-stage polymerization was continuously performed in a liquid full state at an MPaG of an average residence time of 1.59 hr. The slurry containing the polymer sampled directly from the first polymerization vessel was filtered, and the HLMFR of the powder obtained after drying was 0.49.
g / 10 min, and [η] r1 was 3.41 dL / g. The hexane slurry containing the polymer obtained in the first polymerization vessel was flushed with unreacted hydrogen and ethylene in a single depressurization tank having a pressure of 59 KPaG, a temperature of 70 ° C. and an average residence time of 0.3 hr ( H of the polymer in the first stage
LMFR is 0.44 g / 10 min, [η] f1 is 3.
59 dL / g). Thereafter, the mixture was introduced into a second polymerization vessel having an internal volume of 545 L, and the solid catalyst component and alkylaluminum were not added, and the mixture was supplied at 146 L / hr of hexane. Is supplied at a rate of 20 kg / hr, and an ethylene concentration of 0.87 wt% and a hydrogen to ethylene concentration ratio of 0.162 m
ol / mol, the second-stage polymerization was performed under the conditions of a total pressure of 2.0 MPaG and an average residence time of 1.59 hr. The slurry from the second polymerization vessel was subjected to a pressure of 59 KPaG, a temperature of 70 ° C., and an average residence time of 0.2 hr in one auxiliary depressurization tank.
To flush out unreacted hydrogen and ethylene.
The slurry containing the polymer sampled directly from the second polymerization vessel was filtered, and the HLM of the powder obtained after drying was filtered.
FR is 2.76 g / 10 min, [η] r2 is 2.89.
dL / g. Following this, the pressure was 49 KPaG, the temperature was 60 ° C., and the pressure was reduced in one depressurization tank connected in series.
After flushing unreacted hydrogen and ethylene with an average residence time of 0.4 hr, HL
MFR is 2.51 g / 10 min, [η] w is 2.99
A polymer powder having dL / g and a Ti content of 3.2 ppm was obtained.

The same additives and organic peroxide as in Example 2 were added and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet is 2.48 g / 10 mi.
n.

(2) Evaluation of Molded Surface The above-mentioned ethylene polymer pellets were evaluated in the same manner as in Example 1. The skin of the obtained drum molded product and barrel extruded product was good, and no melt fracture or shark skin was observed.

Comparative Example 1 (1) Polymerization The conditions for the first polymerization vessel and the accompanying one depressurization tank were the same as in Example 2. The slurry containing the polymer sampled directly from the first polymerization vessel was filtered, and the [η] r1 of the powder obtained after drying was 2.11 dL / g.
(The MFR of the polymer in the first stage is 0.20 g / 10 m
in, [η] f1 is 2.18 dL / g). Then the second
The second-stage polymerization was carried out in the same manner as in Example 2 except for the polymerization reactor conditions. The HLMFR of the powder obtained by sampling directly from the second polymerization vessel was 3.53 g / 10 min, [η].
r2 was 2.77 dL / g. The slurry from the second polymerization vessel had an average residence time of 0.2 hr in one depressurization tank.
After the unreacted gas was flushed under the same conditions as in Example 2 except that the HMFFR was 3.00 g / 10 min and the [η] w was 2.79 dL /
g and a polymer powder having a Ti content of 1.6 ppm were obtained. [Η]
f2 was 10.1 dL / g, but the production ratio of the polymer was as low as 0.3%.

The same additives and organic peroxide as in Example 2 were added and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet is 2.59 g / 10 mi.
n.

(2) Evaluation of Molded Surface Evaluation was performed in the same manner as in Example 1 using the above-mentioned ethylene polymer pellets. Melt fracture and shark skin were observed on the skin of the obtained drum molded product and barrel extruded product.

Comparative Example 2 (1) Polymerization The conditions for the first polymerization vessel and one accompanying depressurization tank were the same as in Example 2. [Η] r1 of the powder obtained by sampling directly from the first polymerization vessel has a value of 2.12 dL /
g, MFR of the polymer in the depressurization tank is 0.22 g / 10
min and [η] f1 were 2.16 dL / g. Thereafter, the second polymerization was performed in the same manner as in Example 2 except for the conditions of the second polymerization reactor. The HLMFR of the powder obtained by sampling directly from the second polymerization vessel is 3.71 g / 10 mi.
n and [η] r2 were 2.66 dL / g. The slurry from the second polymerization vessel was flushed with unreacted gas under the same conditions as in Example 2 except that the average residence time was set to 2.3 hr in one depressurizing tank, followed by a separation and drying step. , HL
MFR is 2.81 g / 10 min, [η] w is 2.83
A polymer powder having dL / g and a Ti content of 1.5 ppm was obtained.
By extending the residence time, [η] f2 is 15.8 d
L / g increased.

The same additives and organic peroxide as in Example 2 were added and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet is 2.56 g / 10 mi.
n.

(2) Evaluation of Molded Skin Using the above-mentioned ethylene polymer pellets, a sample was obtained by barrel extrusion using a capillary rheometer. Melt fracture and shark skin were observed on the skin of the obtained barrel extruded product.

Comparative Example 3 (1) Polymerization The conditions for the first polymerization reactor were the same as in Example 4. HL of powder obtained by sampling directly from the first polymerization vessel
MFR is 0.44 g / 10 min, powder [η] r1
Was 3.72 dL / g. Thereafter, the hexane slurry containing the polymer obtained in the first polymerization reactor was directly supplied to the second polymerization reactor without passing through the depressurizing tank. In the second polymerization reactor having an internal volume of 545 L, the solid catalyst component and the alkyl aluminum were not added, and hexane was supplied at 146 L / hr. hr at an ethylene concentration of 1.05 wt% and a hydrogen to ethylene ratio of 0.1
The second-stage polymerization was carried out under the conditions of a total pressure of 2.0 MPaG and an average residence time of 1.58 hr while maintaining the concentration at 9 mol / mol.
The slurry containing the polymer sampled directly from the second polymerization vessel was filtered, and the HLM of the powder obtained after drying was filtered.
FR is 3.09 g / 10 min, [η] r2 is 2.75.
dL / g. After discharging unreacted hydrogen and ethylene at a pressure of 59 KPaG, a temperature of 70 ° C. and an average residence time of 1.2 hr in one depressurization tank, the discharge from the second polymerization vessel is subjected to a separation and drying step. After that, HLMFR was 3.1
2g / 10min, [η] w is 2.82dL / g, Ti
A polymer powder having a content of 1.6 ppm was obtained. By bypassing the depressurization tank of the first polymerization vessel, [η] f was a polymer containing no polymer within the specified range.

The same additives and organic peroxide as in Example 2 were added, and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet is 2.93 g / 10 mi.
n.

(2) Evaluation of Molded Surface The above ethylene polymer pellets were evaluated in the same manner as in Comparative Example 2. Melt fracture and shark skin were confirmed on the skin of the obtained barrel extruded product.

Comparative Example 4 (1) Polymerization In a first polymerization vessel having an inner volume of 370 L, 150 L / hr of dehydrated and purified hexane, 36 mmol / hr of tri-i-butylaluminum as an organoaluminum compound (B),
While continuously supplying the solid catalyst component (A) at a rate of 0.51 g / hr and discharging the polymerization content at a required rate,
At 85 ° C., ethylene was supplied at a rate of 19.2 kg / hr, ethylene concentration was maintained at 1.07 wt%, hydrogen was maintained at an ethylene concentration ratio of 0.24 mol / mol, and total pressure was 2.9 M.
The first-stage polymerization was continuously performed under the conditions of PaG and an average residence time of 2.13 hr. The slurry containing the polymer sampled directly from the first polymerization vessel was filtered, and the powder obtained after drying had a [η] r1 of 1.24 dL / g. The hexane slurry containing the polymer obtained in the first polymerization vessel was subjected to pressure of 59 KPaG, 70
Unreacted hydrogen and ethylene were flushed at an average residence time of 0.8 hr at 0 ° C. (the MFR of the polymer in the first stage was 1.8 g / 10 min, and [η] f1 was 1.28)
dL / g). Thereafter, the mixture was introduced into a second polymerization vessel having an internal volume of 545 L, and without adding the solid catalyst component and alkylaluminum, propylene was supplied at 146 L / hr, and ethylene was discharged at 80 ° C. while discharging the polymerization vessel contents at a required speed. It is supplied at a rate of 20.5 kg / hr and has an ethylene concentration of 0.
79wt%, hydrogen to ethylene concentration ratio 0.037mol
/ Mol, and the second-stage polymerization was performed under the conditions of a total pressure of 2.0 MPaG and an average residence time of 1.58 hr. The slurry containing the polymer sampled directly from the second polymerization vessel was filtered, the HLMFR of the powder obtained after drying was 3.18 g / 10 min, and the [η] r2 was 2.70 dL /
g. Effluent from the second polymerization vessel was discharged at a pressure of 59 KPaG, a temperature of 70 ° C., and an average residence time of 1.
After 2 hours, unreacted hydrogen and ethylene were flushed while supplying hydrogen at 500 L / hr. After separation and drying steps, HLMFR was 3.00 g / 10 min.
A polymer powder having [η] w of 2.72 dL / g and a Ti content of 1.7 ppm was obtained. By feeding hydrogen to the depressurizing tank, [η] f2 was reduced.

The same additives and organic peroxide as in Example 2 were added, and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet is 2.72 g / 10 mi.
n.

(2) Evaluation of Molded Surface The same evaluation as in Comparative Example 2 was performed using the above-mentioned ethylene polymer pellets. Melt fracture and shark skin were confirmed on the skin of the obtained barrel extruded product.

Comparative Example 5 (1) Polymerization In Example 3, polymerization was carried out in the same manner as in Example 3 except that the molecular weights to be polymerized in the first polymerization reactor and the second polymerization reactor were reduced, and finally the powder HLMFR30 .9g / 10m
In, [η] w 1.65 dL / g of polymer was obtained.

The same additives and organic peroxide as in Example 2 were added, and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet is 27.2 g / 10 mi.
n. The polymer had an ESCR of 80 hr, a stiffness of 810 MPa, and a Charpy impact value of 6.1 kJ / m ² .

(2) Evaluation of Molded Surface Evaluation was carried out in the same manner as in Comparative Example 2 using the above-mentioned ethylene polymer pellets. No melt fracture or shark skin was observed on the skin of the obtained barrel extruded product. However, [η]
Since w was small, the drum molded article shown in Example 1 was broken in the drop test.

Comparative Example 6 (1) Polymerization In Example 2, polymerization was carried out in the same manner as in Example 2 except that the molecular weight to be polymerized was increased in the second polymerization vessel.
FR 1.02 g / 10 min, [η] w 3.89 dL /
g of polymer was obtained.

The same additives and organic peroxide as in Example 2 were added, and pelletized at 230 ° C. The HLMFR of the obtained ethylene polymer pellet is 0.91 g / 10 mi.
n.

(2) Evaluation of Molded Surface Evaluation was performed in the same manner as in Comparative Example 2 using the above-mentioned ethylene polymer pellets. Melt fracture and shark skin were confirmed on the skin of the obtained barrel extruded product.

[0071]

[Table 1]

[Brief description of the drawings]

FIG. 1 shows a schematic diagram of a polymerization apparatus used in Examples and Comparative Examples.

FIG. 2 shows a schematic diagram of a polymerization apparatus used in Examples and Comparative Examples.

[Explanation of symbols]

A and D are polymerization reactors, B and E are depressurization tanks, G and H are depressurization auxiliary tanks, and C and F are slurry circulation pumps. a to d each indicate a sampling point of the polymer.

Claims (1)

[Claims] 1. In the presence of a highly active Ziegler catalyst, ethylene or ethylene and an α-olefin having 3 to 20 carbon atoms are connected in series using two polymerization reactors, each having a different molecular weight in each polymerization reactor. In the method for producing a polymer, the intrinsic viscosity [η] w of all the obtained polymers is 2.0 to 3.5.
dL / g, and the temperature of at least one depressurization tank connected to each of the two polymerization reactors is 50 to 80 ° C., and the pressure is 30 to 100 KPa.
By adjusting under the conditions of G, the polymer having an intrinsic viscosity [η] f of 7 to 15 dL / g obtained in the depressurization tank is contained in an amount of 0.5 to 10% by weight based on the whole polymer. A method for producing an ethylene-based polymer.