JPH0335324B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a low-density ethylene copolymer composition by gas phase polymerization, which allows gas phase polymerization to be performed with improved operability and improves processability, strength properties, etc. The present invention relates to a method for producing a copolymer composition with excellent physical properties. More specifically, in the present invention, in the presence of an olefin polymerization catalyst comprising a titanium catalyst component and an organoaluminum compound catalyst component, ethylene and a small proportion of carbon atoms
In the method for producing an ethylene copolymer composition by vapor phase copolymerizing the above α-olefin; (i) In the first gas phase polymerization zone, ethylene and propylene or 1-butene are vapor phase copolymerized; (ii) Next, a second gas ^phase polymerization zone is produced. In the presence of the copolymer formed in the first gas phase polymerization zone,
Ethylene and an α-olefin having a larger number of carbon atoms than the α-olefin used in the first gas phase polymerization zone are copolymerized in a gas phase to obtain a product with a density of 0.910 to 0.945 g/cm ³ .
and a copolymer having a molecular weight larger than that of the copolymer formed in the first gas phase polymerization zone is produced in an amount of 70 to 30% by weight of the total amount of the final copolymer composition. The present invention relates to a method for producing an ethylene copolymer composition having a density of 0.910 to 0.945 g/cm ³ . In the presence of an olefin polymerization catalyst consisting of a titanium catalyst component and an organic aluminum compound catalyst component, ethylene and a small proportion of α-olefin are copolymerized to produce a low-density ethylene copolymer with a density of 0.940 g/cm ³ or less. Methods of production are already known. Such low-density ethylene copolymers are particularly attractive for film applications, but among them, α-olefins with carbon atoms of 4 or more, particularly 5 or more, are selected because they exhibit excellent strength properties. Attention has been paid. When attempting to produce such a low-density ethylene copolymer by gas phase polymerization, it is actually difficult to produce a copolymer with good processability and a wide molecular weight distribution in one step; During polymerization in a fluidized bed or agitated fluidized bed, stickiness occurs and long-term continuous operation becomes impossible due to agglomeration of polymer particles and adhesion to the reactor. Also,
Even when adopting a multi-stage method in which the above polymerization is divided into two or more stages and copolymers with different molecular weights are produced in each stage, the same tendency as above occurs when using α-olefin with a large number of carbon atoms. It was easy to appear. Therefore, it has been quite difficult to produce a low-density ethylene copolymer with excellent strength properties and processing properties by gas phase polymerization. As a result of studies to solve these problems, the present inventors divided the gas phase polymerization into two stages, and in the first stage, ethylene and α-olefin with a small number of carbon atoms, particularly propylene or 1-butene, were mixed with a molecular weight of A relatively small copolymer is produced and then
In the presence of the copolymer formed in the first stage, a copolymer having a molecular weight larger than that of the copolymer formed in the first stage is formed from ethylene and an α-olefin having a larger number of carbon atoms than the α-olefin used in the first stage. It has been found that by producing ethylene copolymer compositions, it is possible to obtain ethylene copolymer compositions that have good operability in gas phase polymerization and excellent physical properties such as processability and strength properties. At this time, it was also found that a copolymer composition with excellent transparency can be obtained by controlling the densities of the different types of ethylene copolymers produced in both stages to be in approximately the same range. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an improved method for producing an ethylene copolymer composition using a gas phase copolymerization method. The above objects and many other objects and advantages of the present invention will become more apparent from the following description. According to the present invention, in the presence of an olefin polymerization catalyst comprising a titanium catalyst component and an organoaluminum compound catalyst component, ethylene and a small proportion of carbon atoms
The above α-olefins are subjected to gas phase copolymerization. At this time, (i) in the first gas phase polymerization zone, ethylene and propylene or 1-butene are copolymerized in the gas phase to form a copolymer with a density of 0.910 to 0.950 g/cm ³ in the total amount of the final copolymer composition. 30 to 70% by weight of
(ii) then in a second gas phase polymerization zone, in the presence of the copolymer formed in the first gas phase polymerization zone, ethylene and said first gas phase polymerization zone are produced; α used
- Gas phase copolymerization with α-olefin, which has a larger number of carbon atoms than olefin, to achieve a density of 0.910 or more.
A copolymer having a molecular weight of 0.945 g/cm ³ and greater than the copolymer formed in the first gas phase polymerization zone is added to 70 to 30 of the total amount of the final product copolymer composition.
By producing it at a proportion of weight%,
An ethylene copolymer composition having a density of 0.910 to 0.945 g/cm ³ is prepared. When carrying out the method of the present invention, in order to smoothly perform gas phase copolymerization and take advantage of the advantages of gas phase copolymerization, it is preferable to use a catalyst that can produce a polymer with high activity and excellent fluidity. As such a catalyst, for example, (A) magnesium, titanium and halogen are essential components, and preferably the average particle size is 1.
It is recommended to use a catalyst formed from a highly active solid titanium catalyst component having a diameter of 200μ to 200μ and a geometric standard deviation of particle size distribution σg of less than 2.1, and (B) an organoaluminum compound catalyst component. Preferred highly active solid titanium catalyst component (A)
preferably has a magnesium/titanium (atomic ratio) of 2 to 100, particularly preferably 4 to 70,
The halogen/titanium (atomic ratio) is preferably in the range of 4 to 100, particularly preferably 6 to 40. Further, the specific surface area is preferably 3
m ² /g or more, more preferably about 40 m ² /g or more, even more preferably 100 m ² /g to 800 m ² /g. The catalyst component (A) usually does not eliminate titanium compounds by simple means such as washing with hexane at room temperature. The x-ray spectrum of the magnesium compound is either amorphous regardless of the raw material magnesium compound used for the preparation of the catalyst, or desirably very amorphous compared to that of a common commercially available magnesium dihalide. It is normal for it to be in a state of being The solid titanium catalyst component (A) has, for example, an average particle size of 1 to 200μ, preferably 5 to 100μ, particularly preferably 8 to 50μ, and a geometric standard deviation of particle size distribution of less than 2.1, preferably 1.95 or less. It's good to have one. Here, the particle size distribution of the titanium catalyst component particles can be measured by a light transmission method. Specifically, the catalyst component is diluted to a concentration of around 0.01 to 0.5% in an inert solvent such as decalin, placed in a measurement cell, illuminated with a narrow light, and passed through the liquid in a settled state with particles. The particle size distribution is determined by continuously measuring the light intensity. Based on this particle size distribution, the standard deviation σg is determined from a lognormal distribution function. If a solid titanium catalyst component (A) with an average particle diameter smaller than the above range is used, troubles due to polymer agglomeration or entrainment into the exhaust gas system of the polymerization tank are likely to occur, which is undesirable. If a larger polymer is used, the fluidity during polymerization using a fluidized bed, polymerization vessel, etc. will deteriorate, and it will tend to adhere to the vessel wall or cause polymer aggregation, making it difficult to perform uniform polymerization. Therefore, it is advisable to appropriately select from the above-mentioned preferable conditions. Furthermore, if a particle size distribution with a wide geometric standard deviation σg of 2.1 or more is used, it is likely to cause deterioration of the flow state, polymer aggregation, wall adhesion, etc., which is unfavorable in terms of operation and polymer quality. Therefore, it is preferable to use one with σg of 2.1 or less. As the titanium catalyst component (A), it is preferable to use a spherical material such as a true sphere or an oval sphere. The highly active solid titanium catalyst component (A) may contain other elements, metals, functional groups, electron donors, etc. in addition to the above-mentioned essential components. Furthermore, it may be diluted with an inorganic or organic diluent. Component (A) is also preferably of high performance capable of producing about 2000 g or more of ethylene copolymer per 1 mmol of titanium. The titanium catalyst component (A) that satisfies all of the above-mentioned conditions can be obtained by forming a magnesium compound having an average particle size and particle size distribution, and more preferably a shape within the above-mentioned range, and then using this. It can be obtained by a method of preparing a titanium catalyst component, or a method of bringing a liquid magnesium compound and a liquid titanium compound into contact to form a solid catalyst so as to have the particle properties as described above. Such methods are known, for example, Japanese Patent Application Publication Nos. 55-135102, 55-135103, 56-811,
It is disclosed in No. 56-67311, etc., and can be used in the present invention. A few examples of methods for forming these titanium catalyst components (A) will be briefly described. (1) Magnesium compounds with an average particle size of 1 to 200μ and a geometric standard deviation of particle size distribution σg of less than 2.1: Electron donor complexes such as electron donors and/or organoaluminum compounds and/or halogen-containing silicon compounds. With or without pretreatment with a reaction aid, it is reacted under non-co-milling conditions with a halogenated titanium compound, preferably titanium tetrachloride, which is in a liquid phase under the reaction conditions. (2) A solid component with an average particle size of 1 to 200μ and a geometric standard deviation σg of particle size distribution of less than 2.1 is obtained by reacting a liquid magnesium compound that does not have reducing ability with a liquid titanium compound in the presence of an electron donor. is precipitated. If necessary, a liquid titanium compound, preferably titanium tetrachloride, or the same and an electron donor are reacted under non-co-pulverization conditions. Examples of magnesium compounds used in the preparation of titanium catalyst components include magnesium oxide, magnesium hydroxide, hydrotalcite, carboxylates of magnesium, alkoxymagnesium, allyloxymagnesium, alkoxymagnesium halides, allyloxymagnesium halides, and magnesium dichlorides. halide organomagnesium compound,
Examples include reactants of organomagnesium compounds and electron donors, halosilanes, alkoxysilanes, silanols, aluminum compounds, and the like. As an example of the organoaluminum compound that may be used in preparing the titanium catalyst component, it can be selected from the organoaluminum compound catalyst component (B) that can be used for olefin polymerization, which will be described later. Furthermore, examples of halogen-containing silicon compounds that may be used for preparing the titanium catalyst component include silicon tetrahalides, silicon alkoxy halides, silicon alkyl halides, and halopolysiloxanes. The titanium compound used in the preparation of the titanium catalyst component may be titanium tetrahalide, alkoxytitanium halide, allyloxytitanium halide, alkoxytitanium, allyloxytitanium, etc., and titanium tetrahalide is particularly preferred, with titanium tetrachloride being particularly preferred. . In addition, examples of electron donors that can be used in the production of titanium catalyst components include alcohols, phenols,
Examples include oxygen-containing electron donors such as ketones, aldehydes, carboxylic acids, esters of organic or inorganic acids, ethers, acid amides, acid anhydride alkoxysilanes, nitrogen-containing electron donors such as ammonia, amines, nitriles, isocyanates, etc. can do. More specifically, alcohols having 1 to 18 carbon atoms such as methanol, ethanol, propanol, pentanol, hexanol, octanol, dodecanol, octadecyl alcohol, benzyl alcohol, phenylethyl alcohol, cumyl alcohol, isopropylbenzyl alcohol; Phenols having 6 to 20 carbon atoms which may have a lower alkyl group such as phenol, cresol, xylenol, ethylphenol, propylphenol, nonylphenol, cumylphenol, naphthol; acetone, methyl ethyl ketone,
Ketones having 3 to 15 carbon atoms such as methyl isobutyl ketone, acetophenone, and benzophenone;
2 to 15 carbon atoms such as acetaldehyde, propionaldehyde, octylaldehyde, benzaldehyde, tolualdehyde, naphthaldehyde, etc.
aldehydes; methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octyl acetate, cyclohexyl acetate, ethyl propionate, methyl butyrate, ethyl valerate, methyl chloroacetate, ethyl dichloroacetate, methyl methacrylate, ethyl crotonate , ethyl cyclohexanecarboxylate, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, octyl benzoate, cyclohexyl benzoate, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate, amyl toluate, ethyl benzoate,
Organic acid esters having 2 to 18 carbon atoms, such as methyl anisate, ethyl anisate, ethyl ethoxybenzoate, γ-butyrolactone, δ-valerolactone, coumarin, phthalide, and ethylene carbonate; acetyl chloride, benzoyl chloride, toluic acid chloride , anisyl chloride etc. with 2 or more carbon atoms
15 acid halides; methyl ether, ethyl ether, isopropyl ether, butyl ether,
2 to 20 carbon atoms such as amyl ether, tetrahydrofuran, anisole, diphenyl ether, etc.
ethers; acid amides such as acetic acid amide, benzoic acid amide, and toluic acid amide; amines such as methylamine, ethylamine, diethylamine, tributylamine, piperidine, tribenzylamine, aniline, pyridine, picoline, and tetramethylethylenediamine; Nitriles such as acetonitrile, benzonitrile, tolnitrile;
Examples include alkoxysilanes such as ethyl silicate and diphenyldimethoxysilane. Two or more types of these electron donors can be used. As the organoaluminum compound catalyst component (B), a compound having at least one Al-carbon bond in the molecule can be used, for example, (i) a compound having the general formula R ¹ _n
Al ^{( OR 2} _{) o} H _p
is halogen, m is 0<m≦3, n is 0≦n<3,
p is a number of 0≦p<3, q is a number of 0≦q<3,
and (ii) a Group 1 metal represented by the general formula M ¹ AlR ¹ ₄ (where M ¹ is LiNa or K, and R ¹ is the same as above). Examples include complex alkylated products of aluminum and aluminum. Examples of the organoaluminum compounds that belong to (i) above include the following. General formula R ¹ _n Al
(OR ² ) _3-n (where R ¹ and R ² are the same as above. m
is preferably a number of 1.5≦m≦3). general formula
R ¹ _n AlX _3-n (where R ¹ is the same as above, X is halogen, m is preferably 0<m<3), general formula
R ¹ _n AlH _3-n (where R ¹ is the same as above, m is preferably 2≦m≦3), general formula R ¹ _n Al(OR ² ) _o X _q
(Here, R ¹ and R ² are the same as above. x is halogen, 0<m≦3, 0≦n<3, 0≦q<3, m
+n+q=3). Among the aluminum compounds belonging to (i), more specifically, trialkyl aluminum such as triethyl aluminum and tributyl aluminum,
Besides trialkenylaluminums such as triisoprenylaluminum, dialkylaluminum alkoxides such as diethylaluminum ethoxide, dibutylaluminum butoxide, alkylaluminum sesquialkoxides such as ethylaluminum sesquiethoxide, butylaluminum sesquibutoxide, R ¹ _2.5 Al ( ^OR2 )0.5
Partially alkoxylated alkyl aluminum halides, such as diethylaluminum chloride, dibutyl aluminum chloride, diethylaluminum bromide, ethyl aluminum sesquichloride, butyl aluminum sesquichloride, ethyl aluminum sesquibromide, etc., with an average composition of alkyl aluminum sesquihalides, such as
Partially halogenated alkylaluminiums such as alkylaluminum dihalides such as ethylaluminum dichloride, propylaluminum dichloride, butylaluminum bromide etc., dialkylaluminum hydrides such as diethylaluminum hydride, dibutylaluminum hydride, ethylaluminum dihydride,
Partially hydrogenated alkyl aluminums such as alkyl aluminum dihydrides such as propyl aluminum dihydride, partially alkoxylated and halogenated such as ethyl aluminum ethoxy chloride, butyl aluminum butoxy chloride, ethyl aluminum ethoxy bromide It is an alkyl aluminum. Further, as a compound similar to (i), it may be an organic aluminum compound in which two or more aluminum atoms are bonded via an oxygen atom or a nitrogen atom. Examples of such compounds include (C ₂ H ₅ ) ₂ AlOAl(C ₂ H ₅ ) ₂ ,
( _C4H9 ) _{2AlOAl ( C4H9} ) _{2 ,}

[Catalyst synthesis]

7.2g of anhydrous _MgCl2 in a 200ml flask, 23g of decane
ml and 23 ml of 2-ethylhexanol,
A heating reaction was carried out at 120° C. for 2 hours to obtain a homogeneous solution, and then 1.68 ml of ethyl benzoate was added. Pour 200ml of TiCl ₄ into a 400ml flask and heat to -20°C.
The entire amount of the above homogeneous solution was added dropwise over 1 hour while the solution was kept cooled to 80°C, and then the temperature was raised to 80°C. 80℃
After stirring for 2 hours at 90° C., the solid portion was collected by filtration, suspended in 200 ml of fresh TiCl ₄ and stirred at 90° C. for 2 hours. After the stirring was completed, the solid portion collected by heating was thoroughly washed with hot kerosene and hexane to obtain a titanium catalyst component. The catalyst contains Ti4.5wt%,
Contains Cl60wt%, Mg18wt%, average particle size 15μ,
σg1.25, and the specific surface area was 195 m ² /g. [Catalyst pretreatment] The obtained catalyst slurry was resuspended in hexane to give a concentration of 5 mmol/l in terms of Ti atoms, and then triethylaluminum was added to give a titanium concentration of 15 mmol/l. The catalyst components were supplied at a rate of 20 g per 1 g, and the treatment was carried out at 35°C. [Polymerization] In a gas phase polymerization vessel with a diameter of 40 cm and an internal volume of 400 L, the above pretreated catalyst suspended in n-butane and adjusted to 1.2 mmolTi/l was added at a rate of 1.8 mmolTi/hr and triethylaluminum 50 mmol/hr. Supplied continuously.
At the same time, 6.5Kg/hr of ethylene, propylene and hydrogen gas composition is propylene/ethylene (mole ratio)
= 0.25 and hydrogen/ethylene = 2.3. Pressure 7Kg/cm ² G, temperature 80℃, gas superficial velocity
As a result of copolymerization under the condition of 45 cm/sec, [η ₁ ]=
0.57dl/g, melt flow rate 820, density
A powdered copolymer with good fluidity and a weight of 0.926 g/cm ³ and an average particle size of 350 μ was obtained at a rate of 6.2 Kg/hr. Next, this copolymer was sent to a second stage gas phase polymerization vessel of the same shape, and the pressure was 5 Kg/cm ² G, the temperature was 85°C, the superficial gas velocity was 48 cm/sec, and 4-methyl-1-pentene/4-methyl-1-pentene/
Ethylene and 4-methyl-1 under the conditions of ethylene (molar ratio) = 0.11 and hydrogen/ethylene (molar ratio) = 0.04.
- Gas phase copolymerization of pentene was carried out. the result,
[η] = 2.90dl/g, melt flow rate 0.15g/
10min, density 0.925g/cm ³ , γ ₂ (shear stress 24×
Shear rate at 10 ⁵ dyne/ ^cm2 ) = 270, particle size 440μ
A copolymer with good fluidity could be obtained at 12.2 kg/hr. A 30μ film was made from this copolymer by inflation molding, and its impact strength was measured to be 3500 kg·cm/cm. Comparative Example 1 When 4-methyl-1-pentene was used in place of propylene in the first stage gas phase copolymerization of Example 1, the powder properties were poor and the operation could not be continued. Comparative Example 2 In the second stage gas phase polymerization reactor of Example 1, propylene was used instead of 4-methyl-1-pentene, and the melt flow rate was 0.14 g/10 min, and the density was 0.925 g/10 min.
A copolymer with cm ³ and γ〓 ₂ =250 sec ^-1 was obtained. Similarly 30μ
When the film was molded and its impact strength was measured, it was 1500 kgcm/cm. Example 2 [Polymerization] Using the same apparatus as in Example 1, the pretreated catalyst of Example 1 was continuously supplied at a rate of 1.5 mmol/hr and triethylaluminum at a rate of 60 mmol/hr. At the same time, 8.2Kg/hr of ethylene, 1-butene and hydrogen gas composition is 1-butene/ethylene (mole ratio) =
0.16, hydrogen/ethylene (molar ratio) = 2.0. As a result of copolymerization under the conditions of pressure 8.5Kg/cm ² G, temperature 85℃, and superficial gas velocity 43cm/sec,
A powdered polymer having a melt flow rate of 770, [η]=0.59 dl/g, and a density of 0.930 g/cm ³ was obtained at a rate of 7.5 Kg/hr. Next, in the second stage gas phase polymerization vessel, the pressure was 6.5Kg/cm ²
G temperature 85°C, superficial gas velocity 46 cm/sec, 4-methyl-1-pentene/ethylene (molar ratio) = 0.08,
Gas phase copolymerization of ethylene and 4-methyl-1-pentene was carried out under the conditions of hydrogen/ethylene (molar ratio) = 0.05. As a result, the melt flow rate was 0.21g-
A copolymer with good fluidity and a density of 0.930 g/cm ³ and [η]=2.8 dl/g was obtained at a rate of 14.6 Kg/hr. The film impact strength of this copolymer is 4100Kg・cm/
It was cm. Example 3 In Example 2, the amounts of α-olefin and hydrogen used were changed, and the following results were obtained.

[Table] Copolymer film impact strength is 5900Kg・cm/cm
It was hot.

Claims (1)

[Claims] 1. Ethylene copolymerization by gas phase copolymerization of ethylene and a small proportion of α-olefin having 3 or more carbon atoms in the presence of an olefin polymerization catalyst comprising a titanium catalyst component and an organoaluminum compound catalyst component. In a method for producing a copolymer composition: (i) in a first gas phase polymerization zone, ethylene and propylene or 1-butene are copolymerized in a gas phase to produce a copolymer having a density of 0.910 to 0.950 g/ ^cm3 ; (ii) Then, in a second gas phase polymerization zone, the copolymer formed in the first gas phase polymerization zone is In the presence of ethylene, ethylene and an α-olefin having a larger number of carbon atoms than the α-olefin used in the first gas phase polymerization zone are copolymerized in a gas phase to give a density of 0.910 to
A copolymer having a molecular weight of 0.945 g/cm ³ and greater than the copolymer formed in the first gas phase polymerization zone is added in an amount amounting to 70 to 30% by weight of the total amount of the final copolymer composition. A method for producing an ethylene copolymer composition having a density of 0.910 to 0.945 g/cm ³ . 2. The ethylene content of the final copolymer composition is from about 70% to about 98% by weight.
Manufacturing method described in section. 3 The intrinsic viscosity [η ₂ ] of the copolymer produced in the second gas phase polymerization zone (measured at 135°C in decalin) is
The method according to claim 1, wherein the intrinsic viscosity [η ₁ ] of the copolymer produced in the first gas phase polymerization zone is about 1.2 to about 40 times. 4. The method according to claim 1, wherein the titanium catalyst component is a highly active solid titanium catalyst component containing magnesium, titanium, and halogen as essential components.