JPH0368890B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an ethylene polymer or a copolymer thereof, and more specifically, a method for producing an ethylene polymer or a copolymer thereof with excellent mechanical strength, moldability, etc. continuously for a long period of time with high productivity. Concerning how it can be done. Generally, high-density ethylene polymers are produced using Ziegler type catalysts, and those with high molecular weights are produced in order to improve the mechanical strength of products. In this case, if the molecular weight distribution of the product is narrow, fluidity will be poor during molding, leading to a decrease in productivity, and the resin pressure for molding will be high, so it is necessary to increase the required power. For this reason, conventional attempts have been made to divide the ethylene polymerization process into two or more stages to obtain a product with a wide molecular weight distribution. However, ethylene polymers produced by multi-stage polymerization have a lower die swell than normal ethylene polymers, so when blow molded, the wall thickness becomes thinner, making it difficult to obtain products of consistent quality. . In order to adjust the wall thickness, it is necessary to replace the die, which reduces productivity and is industrially disadvantageous. In addition, moldability is poor due to low melt tension, etc.
Various problems arose. Therefore, the present inventors conducted intensive research on a method for efficiently producing ethylene polymers or copolymers with excellent physical properties by solving the above problems, and after specifying the conditions for each step, three-stage polymerization was carried out. The inventors have discovered that the object can be achieved by carrying out the following steps, and have completed the present invention. That is, the present invention produces an ethylene polymer or copolymer by three-step polymerization using (A) a solid catalyst component containing at least titanium, magnesium, and a halogen, and (B) a catalyst whose main component is an organoaluminium compound. In the method of (g) in a proportion of 12 to 23% by weight of the total polymerization amount, followed by step (b): other α-olefins at a temperature of 70 to 100°C. Step (c) of producing an ethylene polymer or copolymer having a content of 0.5% by weight or less and an intrinsic viscosity [η] of 0.25 to 1.6 dl/g: At a temperature of 60 to 90°C The two steps of producing an ethylene copolymer having a content of other α-olefins of 2 to 30% by weight and an intrinsic viscosity [η] of 2.9 to 5.1 dl/g are carried out in any order. The ratio of polymerization amounts in step (b) and step (c) is (b) step: (c) step =
1: Intrinsic viscosity [η] 2.5-5.2 dl/g, density 0.939-
The present invention provides a method for producing an ethylene polymer or copolymer with a yield of 0.965 g/cm ³ . The catalyst used in the present invention is a catalyst whose main components are (A) a solid catalyst component containing at least titanium, magnesium, and halogen, and (B) an organoaluminum compound component. Here, component (A), a solid catalyst component containing at least titanium, magnesium, and a halogen, is obtained by contacting a magnesium compound and a halogen-containing titanium compound, or an addition compound of this compound and an electron donor, stepwise or primarily. It is a composite solid formed by, and various known types can be used without particular limitation. For example, it can be obtained by reacting a magnesium compound and a chlorine-containing titanium compound in a hydrocarbon solvent with stirring. Some other examples of manufacturing methods include:
No. 34092, Japanese Patent Publication No. 1984-32270, Japanese Patent Publication No. 1987-95382
No., JP-A-54-41985, JP-A-55-729, JP-A-55-13709, JP-A-57-12006, JP-A-57-
There are methods disclosed in various publications such as No. 141409. Magnesium compounds that can be used in the production of component (A) include various compounds that are commonly used as carriers for Ziegler-type catalysts. For example, magnesium chloride, magnesium bromide, magnesium iodide,
Magnesium halides such as magnesium fluoride, magnesium hydroxide, magnesium oxide, magnesium sulfate, magnesium carbonate, hydroxymagnesium halides such as hydroxymagnesium chloride, hydroxymagnesium bromide, hydroxymagnesium iodide, methoxymagnesium, ethoxymagnesium, propoxymagnesium , alkoxymagnesium such as ptoxymagnesium, methoxymagnesium chloride,
Alkoxymagnesium halides such as methoxymagnesium bromide, ethoxymagnesium chloride, ethoxymagnesium bromide, propoxymagnesium chloride, propoxymagnesium bromide, butoxymagnesium chloride, butoxymagnesium bromide,
Allyloxymagnesium halides such as allyloxymagnesium, allyloxymagnesium chloride, allyloxymagnesium bromide, as well as methylmagnesium chloride, methylmagnesium bromide, ethylmagnesium chloride, ethylmagnesium bromide, propylmagnesium chloride, propylmagnesium bromide, butylmagnesium chloride, Examples include alkylmagnesium halides such as butylmagnesium bromide, and mixtures thereof. Furthermore, although the magnesium compound described above can be used as it is, it is more preferable to use one modified with a silicon halide or the like.
For example, a mixture of magnesium dialkoxide and magnesium sulfate modified with silicon tetrachloride and alcohol can be suitably used (Japanese Patent Application Laid-Open No. 40724/1983). The halogen-containing titanium compound that can be used in the production of component (A) may be any divalent, trivalent or tetravalent halogenated titanium compound. Examples of the halogen include bromine and iodine, but chlorine is particularly preferred. For example, titanium tetrachloride (TiCl ₄ ), titanium trichloride (TiCl ₃ ), adduct of titanium trichloride and aluminum chloride (TiCl ₃ 1/3AlCl ₃ ), dichloromethoxytitanium (CH ₃ OTiCl ₂ ), trichloroethoxytitanium (C ₂ H ₅ OTiCl ₃ ), trichloropropoxy titanium (C ₃ H ₇ OTiCl ₃ ), dichlorodipropoxy titanium ((C ₃ H ₇ O) ₂ TiCl ₂ ), dichlorodiethoxy titanium ((C ₂ H ₅ O) ₂ TiCl ₂ ), monochlorotriethoxytitanium ((C ₂ H ₅ O) ₃ TiCl), etc. In the solid catalyst component (A), the above compounds are desirably blended so that the halogen/titanium ratio is in the range of 3 to 200 (mole ratio) and the magnesium/titanium ratio is in the range of 3 to 90 (mole ratio). Next, the organoaluminum compound component of component (B) is a compound having at least one aluminum-carbon bond in the molecule, for example, the general formula
R ₃ Al, R ₂ AlX, RAlX ₂ , R ₂ AlOR, RAl(OR)
X, R _{3 Al 2} (X represents a halogen atom.) Preferred examples of this compound include diethylaluminum monochloride, diisopropylaluminum monochloride, diisobutylaluminum monochloride, dioctylaluminum monochloride, ethylaluminum dichloride, isopropylaluminum dichloride, ethylaluminum sesquichloride, etc. be able to. The amount of component (B) used should be 0.1 to 1000 times the amount of the titanium compound in component (A). A catalyst containing the above-mentioned components (A) and (B) as main components usually has the ability to produce 80 to 400 g of ethylene polymer per 1 mg of titanium. Among the above-mentioned catalysts, especially JP-A-54-161691
No., JP-A-55-40724 and JP-A-55-149307
The catalysts disclosed in each of the publications of No. 1 are suitable. The method of the present invention is carried out by polymerizing ethylene in three stages using the catalyst as described above. First, as the first stage of polymerization, the above-mentioned step (a) is carried out, and the temperature condition for this step should be usually 40°C or higher, preferably 50 to 80°C. If the temperature is less than 40°C, the polymerization reaction will not proceed sufficiently, resulting in low productivity. On the other hand, if the temperature exceeds 80°C, it will be difficult to control the intrinsic viscosity [η] of the resulting polymer, making it difficult to obtain an ethylene polymer with the desired properties or It becomes impossible to obtain a copolymer. Also this (a)
In the process, the content of α-olefins other than ethylene, such as propylene, butene-1, pentene-1, hexene-1, etc., is 0.5% by weight or less, and the intrinsic viscosity [η] is 11 to 26 dl/g, preferably 12-24
Conditions are set to produce dl/g of ethylene polymer or copolymer. In order to realize such conditions, in addition to the above-mentioned temperature, the pressure, the amount of ethylene supplied, the amount of other α-olefins supplied, the amount of hydrogen supplied, etc. may be appropriately selected. Especially the limiting viscosity [η]
can be easily adjusted by using a molecular weight regulator such as hydrogen. In the ethylene polymer or copolymer obtained in step (a), if the content of other α-olefins exceeds 0.5% by weight, it becomes necessary to lower the polymerization temperature, leading to a decrease in productivity. Furthermore, if the intrinsic viscosity [η] of the ethylene polymer or copolymer is less than 11 dl/g, the swell ratio of the ethylene polymer or copolymer finally obtained will be small and unsuitable for blow molding. If it exceeds 26 dl/g, continuous operation becomes difficult and the product becomes unusable due to the appearance of shark skin. Furthermore, in step (a), (a),
It is necessary to adjust the polymerization amount within the range of 12 to 23% by weight, preferably 14 to 20% by weight of the total polymerization amount of the three steps (b) and (c). This is carried out by appropriately selecting the polymerization time depending on the polymerization conditions. If the polymerization amount is less than 12% by weight of the total polymerization amount, the swell ratio of the finally obtained ethylene polymer or copolymer will decrease, and at the same time, the compatibility of the polymers or copolymers produced in each step will deteriorate. Furthermore, the bulk density of the produced polymer is also low, leading to problems such as continuous operation being impossible.
Moreover, if it exceeds 23% by weight, moldability deteriorates, which is not preferable. In the method of the present invention, after the above-mentioned step (a) is completed, steps (b) and (c) are performed in any order. In other words,
In the method of the present invention, the polymerization reaction is carried out in the order of (a) step → (b) step → (c) step, or in the order of (a) step → (c) step → (b) step. Here, in step (b), polymerization is carried out under temperature conditions of 70 to 100°C, preferably 75 to 95°C, as described above. If the temperature condition of this (b) step is less than 70℃, the polymerization reaction will not proceed sufficiently,
Therefore, productivity decreases, and conversely, if the temperature exceeds 100°C, part of the polymer melts and becomes agglomerated, making continuous operation difficult. Further, in this step (b), the properties of the ethylene polymer or copolymer to be produced are determined as well as the above-mentioned temperature conditions. In other words, in step (b), the content of α-olefin other than ethylene is 0.5% by weight or less, and the intrinsic viscosity [η] is
Conditions are set that allow production of ethylene polymer or copolymer at 0.25 to 1.6 dl/g, preferably 0.3 to 1.4 dl/g. Here the content of other olefins is
If it exceeds 0.5% by weight, the amount of solvent-soluble components in the resulting ethylene polymer or copolymer will increase, which is undesirable. Furthermore, under conditions where the intrinsic viscosity [η] is less than 0.25 dl/g, the solvent-soluble components of the obtained ethylene polymer or copolymer increase;
Conditions exceeding 1.6 dl/g are impractical because the fluidity and environmental stress cracking resistance (ESCR) of the ethylene polymer or copolymer decreases. Note that these conditions can only set the properties of the ethylene polymer or copolymer produced when unreacted ethylene monomer or other α-olefin monomer is supplied to step (b) and polymerized. ,(a)
The ethylene polymer or copolymer produced when a mixture (monomer, oligomer, polymer, copolymer mixture) containing a polymer that has undergone some degree of polymerization through step (c) is introduced into step (b). It does not set properties. This also applies to step (c). Therefore, the conditions in step (b) can be independently and easily set without being influenced by the conditions in step (a) or the properties of the produced polymer. In other words,
The polymerization conditions for step (b) (same for step (c)) are determined based on the properties of the polymer and copolymer produced from the monomer raw materials, and are those that are actually produced in step (b). It does not specify the properties of the polymers and copolymers used. Therefore, the conditions for step (b) are the same as those for step (a) or
It can be set in advance regardless of the properties of the polymer etc. produced in step (c). The conditions for this step (b) can be easily set by appropriately selecting the reaction pressure, the amount of ethylene supplied, the amount of hydrogen supplied, etc., as in the case of setting the conditions of the step (a). Next, in step (c), as mentioned above, polymerization is carried out at a temperature of 60 to 90°C, preferably 65 to 85°C. If the temperature condition for this step (c) is less than 60°C, the polymerization rate will be slow and productivity will decrease, and if it exceeds 90°C, a part of the polymer will melt and become agglomerated, making continuous operation difficult. In this step (c), the content of α-olefin other than ethylene is 2 to 15% by weight, preferably 4 to 10% by weight, and the intrinsic viscosity [η]
Conditions are set so as to produce an ethylene polymer or copolymer with a weight of 2.9 to 5.1 dl/g, preferably 3.1 to 4.7 dl/g. Such condition settings are (a)
Step (b) may be carried out by appropriately selecting the pressure, the amount of ethylene supplied, the amount of other α-olefins supplied, the amount of hydrogen supplied, etc., as in the case of step (b). In addition, the conditions for step (c) are set based on the properties of the copolymer produced using ethylene monomer and other α-olefin monomers as raw materials, as in step (b). Using a mixture containing polymers, etc. that has undergone the step or further step (b) as a raw material, actually (c)
It is not based on the properties of the polymer or copolymer itself produced in the process. The conditions for the ethylene copolymer to be produced in step (c) above include other α-olefins (e.g. propylene, butene-1, pentene-1, hexene-1).
1 etc.) is less than 2% by weight, the final ethylene polymer or copolymer
ESCR decreases, and conversely, if it exceeds 30% by weight, rigidity decreases, which is not preferable. Furthermore, the intrinsic viscosity [η] is
Under conditions where it is less than 2.9 dl/g, the ESCR of the ethylene polymer or copolymer obtained as a product decreases, while when it exceeds 5.1 dl/g, the fluidity decreases and it becomes of low practical value. . In the method of the present invention, either the above-mentioned step (b) or step (c) may be performed first, but in either case, the ratio of polymerization amount in step (b) and step (c) is (b)
Step: (c) Step = 1:0.5-1.5, preferably 1:0.6
The polymerization should be carried out while controlling the range of 1.3 to 1.3. If the polymerization in steps (b) and (c) is carried out at a polymerization ratio outside this range, the compatibility of the polymer or copolymer produced in each step will deteriorate, and the resin pressure will increase, which is undesirable. The polymerization method in each step of the method of the present invention may be suspension polymerization, solution polymerization, gas phase polymerization, etc., and continuous method or batch method is also possible.
For example, when performing suspension three-stage polymerization, an inert solvent such as pentane, n-hexane, cyclohexane, heptane, benzene, toluene, etc. can be used as the solvent. In the method of the present invention, by performing the three-stage polymerization as described above, the intrinsic viscosity [η] is 2.5 to 5.2 dl/
g, preferably 3.0 to 4.5 dl/g, density 0.939
~0.965 g/cm ³ , preferably 0.940 to 0.960 g/cm ³ of ethylene polymer or copolymer is produced. This ethylene polymer or copolymer has an intrinsic viscosity [η] in the range of 2.5 to 5.2 dl/g, so it has sufficient melt tension (30 g or more) and good moldability. In addition, since the density is within the range of 0.939 to 0.965 g/ ^cm3 , mechanical strength such as rigidity (Olzen rigidity
7000Kg/ ^cm3 or more) is also excellent. Particularly in blow molding, the melt tension is high, parison breakage can be prevented, and the swell ratio is high at 1.4 or more.
Furthermore, since the dependence of the swell ratio on the shear rate is small, the forming tolerance is wide. In inflation molding, the film has excellent bubble stability, good film appearance, and low resin pressure, resulting in excellent moldability. Furthermore, it has an excellent ESCR of over 200 hours, and has a low solvent soluble component of less than 5%.
Therefore, the ethylene polymer or copolymer obtained by the present invention can be effectively used in a wide range of applications. Furthermore, the method of the present invention has the advantage of eliminating the need for a degassing tank because the polymerization proceeds in step (a), which is the first stage of polymerization, with a small amount of hydrogen supplied. Therefore, according to the method of the present invention, an ethylene polymer or copolymer with excellent properties can be efficiently produced, and it is an extremely valuable method from an industrial perspective. Next, the present invention will be explained in more detail with reference to Examples. Examples 1 to 2 and Comparative Examples 1 to 10 (1) Production of solid catalyst component 1.0 g (8.8 mmol) of magnesium diethoxide and 1.06 g (8.8 mmol) of commercially available anhydrous magnesium sulfate were suspended in 50 ml of n-heptane. Then, 1.5 g (8.8 mmol) of silicon tetrachloride and 1.6 g (35.2 mmol) of ethanol were added, and the reaction was carried out at 80° C. for 1 hour. Next, 5 ml (45 mmol) of titanium tetrachloride was added and the mixture was heated at 98°C for 30 minutes.
Allowed time to react. After the reaction, the mixture was cooled and left to stand, and the supernatant liquid was removed by a decanting method. Next, 100 ml of n-heptane was newly added and washing operations of stirring, standing, and removing the supernatant liquid were performed three times, and then n-heptane was added.
200 ml was added to obtain a dispersion of solid catalyst components.
The amount of titanium supported on this product was determined by a colorimetric method and was found to be 42 mg-Ti/g-support. (2) Production of ethylene copolymer After purging a 2-volume stainless steel autoclave with dry nitrogen, add 0.5% of dry hexane and the above
0.08 mmol of the solid catalyst component produced in (1) (titanium concentration: 0.16 mmol/), 0.21 mmol of triethylaluminum, and 0.59 mmol of diethylaluminum chloride were added. Next, hydrogen was metered so that the ethylene polymer had the intrinsic viscosity [η] shown in Table 1, and ethylene was continuously supplied so that the total pressure of the reactor was 8.7 Kg/cm ³ G. The reaction was carried out at the specified temperature shown in Table 1 for 25 minutes with stirring. Next, in the second stage, after cooling the reactor to 40°C, ethylene, propylene, and hydrogen measured so as to have the intrinsic viscosity [η] shown in Table 1 were added, and the total pressure was 8.3 Kg/cm ³ G. The reaction was carried out with stirring for 120 minutes at the specified temperature shown in the table. In the third stage, 0.5 ml of dry hexane was added, ethylene, propylene, butene-1, and hydrogen measured to give the intrinsic viscosity shown in Table 1 were added, and the total pressure was 6 Kg/cm ³ , as shown in Table 1. The reaction was carried out for 30 minutes with stirring at the predetermined temperature shown in . After the reaction was completed, the obtained ethylene copolymer composition was washed and dried, and its physical properties were measured. The results are shown in Tables 1 and 2.

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Claims (1)

[Scope of Claims] 1. An ethylene polymer or copolymer is produced by three-step polymerization using (A) a solid catalyst component containing at least titanium, magnesium and halogen and (B) a catalyst whose main component is an organoaluminum compound. In the manufacturing method, as the first step, (a) step: At a temperature of 50 to 80°C, the content of other α-olefins is 0.5% by weight or less, and the intrinsic viscosity [η] is 11 to 26 dl. /g of ethylene polymer or copolymer at a proportion of 12 to 23% by weight of the total polymerization amount, followed by step (b): At a temperature of 70 to 100°C, other α - Step of producing an ethylene polymer or copolymer having an olefin content of 0.5% by weight or less and an intrinsic viscosity [η] of 0.25 to 1.6 dl/g; and (c) step: at a temperature of 60 to 90°C. Under the following conditions, the two steps of producing an ethylene copolymer having a content of other α-olefins of 2 to 30% by weight and an intrinsic viscosity [η] of 2.9 to 5.1 dl/g can be carried out in any order. At the same time, the ratio of polymerization amount in step (b) and step (c) is (b) step: (c) step =
1: Intrinsic viscosity [η] 2.5-5.2 dl/g, density 0.939-
A method for producing an ethylene polymer or copolymer having a weight of 0.965 g/cm ³ .