JPH06172465A - Production of propylene-ethylene block copolymer - Google Patents

Abstract

PURPOSE:To produce the subject copolymer having high impact resistance, rigidity and processability in high productivity by polymerizing a propylene-rich component using a catalyst composed of a Ti-containing solid, an organic Al compound, an electron donor, etc., and polymerizing ethylene in the presence of an Si compound. CONSTITUTION:A solvent 6 such as heptane and a catalyst 5 composed of a solid catalyst component, an alkyl Al compound and an electron donative compound are supplied to a polymerizer 1. Propylene is supplied to the polymerizer through a feed line 8 and polymerized. The produced slurry is transferred to a polymerizer 2, hydrogen is supplied through a feed line 10 and the polymerization is continued until the amount of block segment of a propylene homopolymer or a propylene-ethylene copolymer reaches 60-95wt.% based on the total copolymer. The product is transferred through a flushing tank F to reactors 3, 4 and polymerized by supplying an alkoxysilane compound and etylene through the feeding lines 7, 9, respectively, to form a block segment of ethylene homopolymer or copolymer with propylene and obtain the objective propylene-ethylene block copolymer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a propylene-ethylene block copolymer, and more specifically, it produces a copolymer having excellent impact resistance and rigidity, less fish eyes, and good processability. Regarding the method.

[0002]

2. Description of the Related Art Highly crystalline polypropylene obtained by polymerizing propylene using a stereoregular catalyst has a wide range of uses as a material having excellent rigidity and heat resistance as a thermoplastic resin. On the other hand, a propylene / ethylene block copolymer having improved impact resistance at low temperature, which is a drawback of polypropylene, is produced by a propylene / ethylene block copolymerization method in which propylene and ethylene are polymerized or copolymerized in two or more steps. It is known to be done.

Further, in order to improve the productivity, polymerization of propylene or a mixture of propylene and a small amount of ethylene is continuously carried out in the first stage using a stereoregular catalyst, and propylene and ethylene are continuously copolymerized in the second and subsequent stages. It is known that a non-crystalline propylene / ethylene copolymer containing a small amount of propylene is continuously produced to continuously produce a propylene / ethylene block copolymer having an excellent balance of impact resistance and rigidity.

These methods include changing the polymerization conditions such as the polymerization pressure, the polymerization temperature, the amount of the polymerization or copolymerization monomer or the coexisting hydrogen concentration in order to control the polymerization ratio and the chain length of each block segment in the first and second stages. A compound that suppresses the polymerization activity such as an electron donating compound is added and controlled after the latter stage of the copolymerization reaction.

[0005]

In the method of changing the above-mentioned polymerization conditions, it is very difficult to set the corresponding polymerization conditions because polymers having different compositions are produced at each stage. However, there is a problem in that a product having a poor quality balance such as processability, a large number of lumps when a film or sheet is formed, and only a product having a poor appearance and a low commercial value can be obtained.

Further, a method of adding and controlling a compound which suppresses the polymerization activity such as an electron-donating compound after the block copolymerization reaction is carried out by a compound such as an amine compound or a ketone compound which suppresses the polymerization activity. , Electron-based compounds such as ester-based compounds, ether-based compounds, acid amide-based compounds, phosphoric acid amide-based compounds (Japanese Patent Publication No. 63-41929, Japanese Patent Publication No. 03-23090), acetylene-based compounds, and diene-based compounds are used. , These compounds react with alkylaluminum halides, hexane, heptane,
It is difficult to remove it from the polymer because it forms a complex that does not dissolve in the solvent used for polymerization of toluene, etc., and monomers such as propylene and ethylene, and depending on the supply amount, a large amount of these compounds may remain in the polymer. There is a problem that the quality is deteriorated and the odor is not preferable.

Further, a propylene / ethylene block copolymer using a highly active carrier catalyst obtained by bringing a transition metal compound such as titanium tetrachloride and an electron donating compound into contact with a carrier containing magnesium halide as a main component is continuously prepared. In the production method, the effect is not sufficient even if these compounds are used, and in the polymerization using these highly active catalysts, a demineralization process or a solvent such as hexane, heptane or toluene, propylene or ethylene, etc. The above-mentioned electron-donating organic compound cannot be removed from the polymer by using the above-mentioned electron-donating organic compound because the purification is carried out to such an extent that the excess co-catalyst is removed by washing with the monomer. However, there was a problem that a large amount remained in the polymer, which was not preferable in terms of quality and odor.

[0008]

[Means for Solving the Problems] The present inventors have solved the above problems and have a good quality balance such as impact resistance, rigidity, and processability, and do not cause scratches when forming a film or sheet. The present invention has been completed by earnestly investigating a method for producing a highly valuable propylene-ethylene block copolymer with high productivity.

That is, the present invention uses a catalyst comprising a solid catalyst component containing a titanium compound, an alkylaluminum compound and an electron donating compound to continuously produce propylene, ethylene or a mixture of propylene and ethylene in two or more stages. In the method for producing a propylene-ethylene block copolymer by agglomerative polymerization, a) a propylene homoblock segment or 94 mol% or more of propylene units and 4 mol% occupying 60 to 95% by weight of the total block copolymer. A propylene / ethylene copolymer block segment (A block segment) containing the following ethylene units, and b) an ethylene homoblock segment or 20 mol% or more of ethylene units and 80 mol which occupies 5 to 40% by weight of the total block copolymer. % Ethylene consisting of less than propylene units Block segments rich in (B block segments), it is composed of two block segments of the, A block segment chain length (intrinsic viscosity [η]
₁ ) is 0.8 to 3.5, the B block segment chain length (intrinsic viscosity [η] ₂ ) is 2.0 to 15, and their ratio [η] ₂
In carrying out the copolymerization so that / [η] ₁ falls within the range represented by the following general formula (Formula 2), the A block segment is continuously polymerized as the first step, and then the B block is used in the second step and thereafter. Polymerization activity and B block segment chain length in the presence of an alkoxysilane compound containing hydrogen and a polar group during continuous polymerization of segments
Propylene characterized by adjusting ([η] ₂ )
Method for producing ethylene block copolymer

[0010]

[Equation 2] 1 <[η] ₂ / [η] ₁ ≤18.

The solid catalyst component containing a titanium compound used in the present invention is titanium trichloride, titanium tetrachloride, a complex of titanium trichloride and an electron-donating compound, which is known as a highly stereoregular catalyst, or a halogenated compound thereof. A solid catalyst component containing titanium halide supported on an inorganic carrier compound such as magnesium with or without an electron donating compound, and a solid catalyst component obtained by contacting a titanium compound with a magnesium compound and an electron donor. The solid catalyst component (1) is used as a catalyst in combination with an alkylaluminum compound and, if necessary, an electron donating compound.

As the alkylaluminum compound, a trialkylaluminum having 1 to 3 carbon atoms having 1 to 12 carbon atoms, a dialkylaluminum halide, an aluminum dihalide, or an aluminoxane compound having an Al-O-Al bond can be used. . For example, triethyl aluminum, diethyl aluminum chloride, diethyl aluminum ethoxide, ethyl aluminum dichloride, ethyl aluminum dihydride, ethyl aluminum sesquichloride, ethyl aluminum sesquiethoxide, triisopropyl aluminum, diisopropyl aluminum chloride, isopropyl aluminum dichloride, isopropyl aluminum dihydride, Tributyl aluminum, dibutyl aluminum chloride, dibutyl aluminum butoxide, butyl aluminum dichloride, triisobutyl aluminum, diisobutyl aluminum chloride, isobutyl aluminum dichloride, trihexyl aluminum, trioctyl aluminum, isoprenyl aluminum Further tetramethyl aluminoxane, include methyl aluminoxane, they may be mixed alone or two or more.

As the electron donating compound, a compound containing an atom such as oxygen, nitrogen, sulfur, phosphorus or silicon is used. For example, aliphatic ether, aromatic ether, aliphatic alcohol, aromatic alcohol, aliphatic ester, aromatic ester, phosphoric acid ester, silicic acid ester, cyclic oxygen-containing compound, amine compound or ketone compound, acid amide compound, phosphoric acid Amide compounds, acetylene compounds, diene compounds, cyclic nitrogen-containing compounds such as piperidine, pyrrole and quinoline, acid anhydrides or the following general formula (Formula 1)
Examples of the organic silicon compound represented by are: These may be used alone or in combination of two or more kinds.

[0014]

## STR1 ## ^{_{R n S (OR ') 4}} -n ( wherein, R and ^R' are different hydrocarbon residues same or mutually, n is an integer of 1, 2 or 3.)

The alkoxysilane compound containing a polar group used for controlling the polymerization activity and the B block segment chain length ([η] ₂ ) after the second step in the present invention includes oxygen, nitrogen, sulfur, phosphorus and silicon. And a silane compound having an Si—O bond containing an atom such as a substituent.
For example, silicone oil compound modified with alcohol, ether, ester, cyclic oxygen-containing compound, tris (2-
(Methoxyethoxy) methylsilane, tris (2-methoxyethoxy) vinylsilane, 3-glycidoxypropyltrimethoxysilane, 1,3-bis (3-glycidoxypropyl)
1,1,3,3-Tetramethyldisiloxane, γ-aminopropyltriethoxysilane, aminoethylpropyldimethoxymethylsilane, tetrahydrofurfryloxytrimethylsilane, dimethoxy-3-glycidoxypropylmethylsilane, 1,3-bis (3-Hydroxypropyl) 1,1,3,3-tetramethyldisiloxane, 2- (2-ethoxyethoxy) ethoxytrimethylsilane, tetrakis (2-methoxyethoxy) silane and the like are used. Use of these silane compounds The amount varies depending on the compound used, but is usually 0 per 1 mol atom of titanium in the solid catalyst component containing titanium halide.
Amounts in the range of 01 to 10 molar times, preferably 0.1 to 5 molar times are used.

The polymerization method of the present invention comprises continuously polymerizing propylene, ethylene or a mixture of propylene and ethylene in two or more steps to produce a propylene-ethylene block copolymer. Polymeric
A propylene homoblock segment or a propylene / ethylene copolymer block segment containing 96 mol% or more of propylene units and 4 mol% or less of ethylene units occupying 60 to 95% by weight (hereinafter referred to as A block segment), b). Ethylene homoblock segment or 20 mol% accounting for 5 to 40% by weight of all block copolymers
It is composed of two types of block segments: a block segment rich in ethylene units composed of the above ethylene units and 80 mol% or less of propylene units (hereinafter referred to as B block segment). If the amount of the A block segment is less than 60% by weight of the total block copolymer, the impact strength at low temperature is insufficient, and if it exceeds 95% by weight, the elastic strength is insufficient, which is not preferable.

In the present invention, when the A block segment is continuously polymerized as the first step, it is polymerized so that the A block segment chain length ([η] ₁ ) is in the range of 0.8 to 3.5, and then the second step. In the subsequent continuous polymerization of the B block segment, the polymerization activity and the B block segment chain length ([η] ₂ ) are 2.0 to 15 by adding hydrogen and an alkoxysilane compound containing the above polar group.
The block segment chain length ratio [η] ₂ / [η] ₁ satisfies the above general formula (Equation 2), that is, the value of [η] ₂ / [η] ₁ It is essential to carry out the copolymerization in such a range that is greater than 1 and does not exceed 18. When this value is 1 or less, the resulting copolymer is inferior in physical properties such as impact strength at low temperature, tensile elasticity and elongation.
If it exceeds 18, the impact strength at low temperature is insufficient and it is difficult to prevent the generation of fish eyes, which is not preferable.

Here, the alkoxysilane compound containing a polar group is added continuously or intermittently, but it is indispensable that it is after the completion of the polymerization in the first step, and a flushing tank or the like is installed before the second step. Or the B block segment may be polymerized in the presence of the alkoxysilane compound. Further, in order to maintain the molecular weight of the hydrogen produced in both the A block segment and the B block segment at a desired value, the molecular weight can be adjusted in the same manner as a known method using hydrogen in general. .

The polymerization conditions are not particularly limited, and a solvent polymerization method using an inert medium, a bulk polymerization method in which substantially no inert medium is present, or a gas phase polymerization method can be used.
Generally, the polymerization temperature is −100 to 200 ° C., and the polymerization pressure is normal pressure to 100 kg / cm ² -G. The pressure is preferably −100 to 100 ° C. and atmospheric pressure to 50 kg / cm ² -G.

[0020]

EXAMPLES The present invention will be described in more detail with reference to the following examples.

Example 1 A polymerization apparatus as shown in FIG.
Continuous polymerization of the A block segment of the stage was carried out, and this was continuously fed to the second stage of the polymerization tanks 3 and 4, and the B block segment was continuously polymerized. 1, 2 in FIG.
Indicates the first stage polymerization tank. A flushing tank F is installed between the first step and the second step, and an appropriate amount of hydrogen gas as a monomer and a molecular weight modifier is installed in each tank separately. An autoclave with an internal volume of 200 liters equipped with a stirrer was used for each polymerization tank and flushing tank.

60 liter / hour of heptane was added to the polymerization tank 1.
Titanium trichloride as a catalyst (manufactured by Solvay Co., TiCl ₃
(01 catalyst) 37.8 g / hour and 137.6 g / hour of diethylaluminum chloride were continuously supplied, and the slurry obtained by polymerization was continuously sent to the polymerization tank 2 for further polymerization. Polymerization tanks 1 and 2 have a temperature of 70 ° C and a pressure of 2.6 kg / cm ² -G each.
, 2.3 kg / cm ² -G, hydrogen concentration in the vapor phase is 1 each
Propylene was supplied so as to be adjusted to 1 mol% and 14 mol%. The slurry leaving the polymerization tank 2 is a flushing tank F.
It was supplied to the polymerization tank 3 via Flushing tank F
Prepared at 70 ℃, 0.5kg / cm ² -G, and used tris (2-methoxyethoxy) methylsilane 0.12 as an alkoxysilane compound.
Mol / hour was added.

The temperature of the polymerization tanks 3 and 4 was 55 ° C., and propylene was supplied at 2.4 kg / hour and 0.8 kg / hour, respectively,
The gas composition of the gas phase is ethylene / (ethylene + propylene) 0.42, 0.40, hydrogen concentration 7.2 mol%, 6.
Polymerization was carried out by supplying ethylene and hydrogen to 1 mol%. The slurry discharged from the polymerization tank 4 was sent to a post-treatment tank, deactivated the catalyst with methanol, further neutralized with a caustic soda aqueous solution, washed with water, separated with a filter to separate the polymer, and dried to obtain a product.

On the way, the slurry was sampled in the flushing tank F and the post-treatment tank, and the reaction amount per catalyst and [η] (1
When the intrinsic viscosity measured with a tetralin solution at 35 ° C was measured, the reaction amount in the flushing tank F (A block segment) was 1030 g / g-catalyst, [η] ₁ was 1.25, and the post-treatment tank (product- B block segment obtained by converting from A block segment), the reaction amount is 190 g / g-catalyst,
[Η] ₂ was 6.0. Also, [η] ₂ / [η] ₁ is
It was 4.8.

Next, 0.1% by weight of a phenolic stabilizer and 0.1% by weight of calcium stearate were added to the polymer of the product and pelletized by an extruder of 30 mmφ. A test piece was prepared from the obtained pellet by an injection molding machine. Further, a film having a thickness of 30 μ was formed with a T-die of 40 mmφ, and the number of foreign matters was measured with a fish eye counter. The results including other physical properties are shown in Table 1.

Comparative Example 1 The same procedure as in Example 1 was carried out except that tris (2-methoxyethoxy) methylsilane was not added in the flushing tank F. Similarly, in the A block segment, the reaction amount was 10
50 g / g-catalyst, [η] ₁ was 1.27, and the reaction amount of the B block segment was 240 g / g-catalyst, [η] ₂ was 5.6. Moreover, [η] ₂ / [η] ₁ was 4.4. The results are shown in Table 1, and the number of fish eyes was as large as 1000 or more, which was unacceptable as a product.

Comparative Example 2 The same procedure as in Example 1 was carried out except that 0.12 mol / hour of diethylene glycol dimethyl ether was added instead of tris (2-methoxyethoxy) methylsilane in the flushing tank F. The amount of 1010 g / g-catalyst, [η] ₁ was 1.23, and the reaction amount of the B block segment was 170 g / g-catalyst, [η] ₂ was 5.8. In addition, [η] ₂ / [η] ₁ was 4.7. The results are shown in Table 1. The product had a strong ether odor.

Example 2 The same procedure as in Example 1 was carried out except that the addition amount of tris (2-methoxyethoxy) methylsilane was changed to 0.06 mol / hour in the flushing tank F. Similarly, in the A block segment, the reaction amount was changed. Is 1080 g / g-catalyst, [η] ₁ is 1.26,
The reaction amount of B block segment is 230g / g-catalyst, [η]
₂ was 5.7. Further, [η] ₂ / [η] ₁ was 4.5. The results are shown in Table 1.

Example 3 The same procedure as in Example 2 was carried out except that the addition amount of tris (2-methoxyethoxy) methylsilane was changed to 0.24 mol / hour in the flushing tank F. Similarly, in the A block segment, the reaction amount was changed. Is 1020 g / g-catalyst, [η] ₁ is 1.29,
The reaction amount of B block segment is 170g / g-catalyst, [η]
₂ was 5.7. Moreover, [η] ₂ / [η] ₁ was 4.4. The results are shown in Table 1.

Example 4 In the flushing tank F, 1,3-bis (3-glycidoxypropyl) 1,1,3,3-tetramethyldisiloxane 0.12 mol / hour was used instead of tris (2-methoxyethoxy) methylsilane. The same procedure as in Example 1 was performed except that
In the block segment, the reaction amount is 1020 g / g-catalyst,
[Η] ₁ was 1.27, the reaction amount of the B block segment was 200 g / g-catalyst, and [η] ₂ was 6.0. Also,
[Η] ₂ / [η] ₁ was 4.7. The results are shown in Table 1.

Comparative Example 3 Hydrogen was added to the polymerization tanks 1 and 2 so that the hydrogen concentration in the gas phase portion was different.
2.0 mol%, 2.8 mol%, gas in the gas phase part of the polymerization tanks 3 and 4.
The ethylene composition is ethylene / (ethylene + propylene)
0.42, 0.40, hydrogen concentration will be 30 mol%, 28 mol%
Example except that propylene, ethylene and hydrogen were supplied
When I went to the same way as No. 1, the A block segment
Then, the reaction amount is 1010 g / g-catalyst, [η]₁Is 2.03,
The reaction amount of B block segment is 180g / g-catalyst, [η]
₂Was 1.96. Also, [η] ₂/ [Η]₁Is 0.97
there were. The results are shown in Table 1, which shows impact strength and tensile strength at low temperatures.
The result was inferior elongation at break.

[0032]

[Table 1]

[0033]

By carrying out the method of the present invention, the quality balance of impact resistance, rigidity, workability, etc. is good, and it has a high commercial value that does not cause scratches when a film or sheet is formed, and has an odor. A propylene-ethylene block copolymer free from the above problem can be produced with high productivity and is industrially extremely valuable.

[Brief description of drawings]

FIG. 1 is a flow chart of an embodiment for facilitating understanding of the present invention.

[Explanation of symbols]

 1 polymerization tank (first tank of A block segment) 2 polymerization tank (second tank of A block segment) 3 polymerization tank (first tank of B block segment) 4 polymerization tank (second tank of B block segment) 5 catalyst Charge line 6 Solvent supply line 7 Alkoxysilane compound supply line 8 Monomer (propylene) supply line 9 Monomer (ethylene) supply line 10 Hydrogen supply line 11 Slurry discharge line F Flushing tank P Slurry feed pump

Claims (1)

[Claims] 1. A propylene, ethylene or a mixture of propylene and ethylene is continuously polymerized in two or more stages by using a catalyst comprising a solid catalyst component containing a titanium compound, an alkylaluminum compound and an electron donating compound. In the method for producing a propylene-ethylene block copolymer by: a) a propylene homoblock segment or 94 mol% or more of propylene units and 4 mol% or less of ethylene, which accounts for 60 to 95% by weight of the total block copolymer. A propylene / ethylene copolymer block segment (A block segment) containing units, and b) 5 to 40% by weight of the total block copolymer of ethylene homoblock segment or 20 mol% or more ethylene units and 80 mol% or less. A block rich in ethylene units composed of propylene units Segment (B block segments), is composed of two block segments of the, A block segment chain length (intrinsic viscosity [η]
₁ ) is 0.8 to 3.5, the B block segment chain length (intrinsic viscosity [η] ₂ ) is 2.0 to 15, and their ratio [η] ₂
In carrying out the copolymerization so that / [η] ₁ falls within the range represented by the following general formula (Formula 1), the A block segment is continuously polymerized as the first step, and then the B block is used in the second step and thereafter. Polymerization activity and B block segment chain length in the presence of an alkoxysilane compound containing hydrogen and a polar group during continuous polymerization of segments
Propylene characterized by adjusting ([η] ₂ )
Process for producing ethylene block copolymer. [Equation 1] 1 <[η] ₂ / [η] ₁ ≤18