JPH069736A - Production of propylene block copolymer - Google Patents

Abstract

PURPOSE:To obtain a copolymer of a high molecular weight by polymerizing propylene in the presence of a specified catalyst system, adding an alkylaluminoxane to the reaction system, and polymerizing propylene with another alpha-olefin. CONSTITUTION:Propylene and at most 10wt.% alpha-olefin are polymerized in an inert hydrocarbon in the presence of a catalyst system comprising a solid containing titanium trichloride and an alkylaluminum compound of the formula: AlR3-nXn (wherein R is 1-8 C alkyl; X is halogen; and n is 0-3). An alkylaluminoxane is added to the reaction system without deactivating the catalyst system, and propylene and another alpha-olefin are copolymerized to obtain a propylene block copolymer having a weight-average molecular weight of 400000 or above when measured on the xylene-solubles at 20 deg.C.

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 block copolymer having high rigidity and excellent impact strength.

[0002]

2. Description of the Related Art Crystalline polypropylene produced by using a Ziegler type catalyst has excellent properties such as rigidity and heat resistance, but it is especially used for automobiles, electric products, sports equipment and the like. In the above, the impact strength, especially the high impact strength at low temperature, is not always satisfactory, and improvement is desired. To improve impact strength,
A propylene block copolymer has been proposed in which a crystalline polypropylene is block-copolymerized with a rubbery copolymer of propylene and α-olefin.

As a method for producing a propylene block copolymer, in the presence of a Ziegler type catalyst composed of a combination of a titanium trichloride-containing solid and an organoaluminum compound,
A method of block-copolymerizing propylene and α-olefin by a slurry polymerization using an inert organic solvent, a gas phase polymerization, or a combination of a bulk polymerization and a gas phase polymerization has been proposed. In particular, the production process by a combination of bulk polymerization in which a monomer in a liquid state is polymerized in a solvent and gas phase polymerization in which a monomer is brought into contact with a catalyst in a gaseous state are used for isolation of a produced polymer and recovery of unreacted monomer. It has the advantage of being easy.

For example, in JP-A-54-123191, bulk polymerization of propylene is carried out in the first step using a catalyst composed of a titanium trichloride-containing solid and an organoaluminum compound, followed by a second step. With propylene and other α-
Disclosed is a method for obtaining a propylene block copolymer by performing gas phase polymerization with an olefin.

In Japanese Patent Publication No. 55-7464, a trialkylaluminum is added at the time of polymerization in the second stage,
Although a method of increasing the polymerization activity is disclosed, since the rubber-like copolymer component has a low molecular weight, the moldability (spiral flow) during processing is deteriorated, and at the same time, the impact strength improving effect of the block copolymer is small. There's a problem.

[0006]

It is an object of the present invention to produce a propylene block copolymer having a high copolymerization activity and a high molecular weight of a rubbery copolymer component of propylene and α-olefin using a titanium trichloride catalyst. To provide.

[0007]

The present invention relates to a titanium trichloride-containing solid and a compound of the formula AlR _3-n X _n (wherein R is an alkyl group having 1 to 8 carbon atoms, X is halogen and n is 0). A method of producing a propylene block copolymer having a weight average molecular weight of the xylene-soluble part at 20 ° C. of not less than 400,000, using a catalyst system consisting of an alkylaluminum compound represented by a larger number of less than 3). In the first step, propylene or propylene and a small amount of other α-olefin are polymerized, and subsequently, in the second step, alkylaluminoxane is added to the propylene without deactivating the catalyst system. It relates to a method for producing a propylene block copolymer, which comprises polymerizing with an α-olefin other than propylene.

As the solid titanium trichloride catalyst in the present invention, any conventionally known catalyst can be used. For example, a method of treating titanium tetrachloride obtained by reducing titanium tetrachloride with an organoaluminum compound with a complexing agent and subsequently with titanium tetrachloride, a method of reducing titanium tetrachloride with metallic aluminum A method of further treating titanium chloride (eutectic containing 1/3 mol of aluminum trichloride with respect to 1 mol of titanium trichloride) with an electron donor, a method of pulverizing and activating titanium trichloride with a ball mill, etc. Can be manufactured by. These titanium trichlorides are disclosed in JP-B-55-8451 and JP-B-54-
28316, JP 47-34478, JP 58-36928, and JP 59-12905.
JP-A-59-13630, JP-A 1-2
It is known in Japanese Patent Publication No. 75607 and the like.

In the present invention, the formula AlR _3-n X _n (in the formula, R is an alkyl group having 1 to 8 carbon atoms, X is halogen, n
Is a number greater than 0 and less than 3. ), For example, dimethyl aluminum monochloride, diethyl aluminum monochloride, dibutyl aluminum monochloride, dinormal propyl aluminum monochloride, methyl aluminum sesquichloride, ethyl aluminum sesquichloride, butyl aluminum sesquichloride, butyl. Aluminum sesquiclobromide etc. can be mentioned. The amount of the above-mentioned alkylaluminum compound used is 0.5 to 20, preferably 1 to 10, in terms of the element ratio of aluminum to titanium (Al / Ti) in the titanium trichloride-containing solid.

The alkylaluminoxane used in the present invention is dispersed in a trialkylaluminum and a solvent as disclosed in, for example, JP-A-59-95292 and JP-A-62-230802. It is obtained by reaction with water. Examples of the trialkyl aluminum include trimethyl aluminum, triethyl aluminum, tripropyl aluminum, tributyl aluminum, trihexyl aluminum, trioctyl aluminum and the like. Examples of the solvent in which water is dispersed include benzene, toluene, xylene, ether and the like. As an inorganic compound utilizing water of crystallization,
Examples thereof include magnesium chloride, magnesium sulfate, aluminum sulfate and copper sulfate. The amount of alkylaluminoxane used is an element ratio of aluminum to titanium (Al / Ti) of titanium trichloride-containing solid, and is preferably 0.1 to 3.0, and particularly preferably 0.3 to 2.5. . When the amount of alkylaluminoxane used is less than the above range, the copolymerization yield is not sufficiently increased, which is not preferable. On the other hand, if the amount exceeds the above range, the weight average molecular weight of the rubbery copolymer becomes small, which is not preferable.

The first-stage polymerization may be homopolymerization of propylene or copolymerization of propylene with a small amount of other α-olefin. Examples of the α-olefin include ethylene, butene-1, 4-methylpentene-1 and the like. The proportion of α-olefin other than propylene in the crystalline polymer obtained in the first step is preferably an amount such that the characteristics of polypropylene are not lost, for example, 10% by weight or less. If the proportion of α-olefin other than propylene in the crystalline polymer exceeds 10% by weight, the amount of low crystalline polymer by-products increases. If necessary, hydrogen may be added as a chain transfer agent in order to adjust the molecular weight of the produced polymer.

In the first step, after the crystalline polymer is produced by homopolymerization of propylene or copolymerization of propylene with a small amount of other α-olefin, the above catalyst system is not deactivated, Unreacted monomers in the polymerization are partially removed, then in a second step, alumoxane is added in the presence of the crystalline polymer, without deactivating the catalyst system described above, to give propylene and A rubbery copolymer with an α-olefin other than propylene is produced.

The ratio of the rubbery copolymer of propylene and the α-olefin other than propylene obtained in the second step is
It is usually 3 to 30% by weight, more preferably 5 to 15% by weight, based on the total amount of the block copolymer. The proportion of α-olefin other than propylene in the rubbery copolymer is preferably 10 to 40% by weight. The weight average molecular weight of the rubbery copolymer obtained in the present invention is 400,000 or more, more preferably 1,000,000 or more. When the weight average molecular weight of the rubbery copolymer is less than 400,000, the effect of improving the impact strength of the propylene block copolymer becomes small.

As the polymerization mode of the present invention, slurry polymerization in an inert hydrocarbon solvent, bulk polymerization in which a monomer in a liquid state is polymerized therein as a solvent, gas phase polymerization in which a monomer is brought into contact with a catalyst in a gas state, Alternatively, these can be combined to carry out the polymerization.

The bulk polymerization is preferably carried out under conditions of temperature and pressure that can keep propylene or a mixed monomer of propylene and another α-olefin in a liquid state. The polymerization temperature is usually 30 to 90 ° C, preferably 50 to 80 ° C. The polymerization time is usually 5 minutes to 5 hours.

The slurry polymerization is carried out by introducing propylene or a mixed monomer of propylene and another α-olefin in the presence of an inert hydrocarbon. Examples of the inert hydrocarbon include n-pentane, isopentane, n-hexane,
Examples thereof include n-heptane, n-octane, isooctane, n-decane, benzene, toluene, xylene and cyclohexane. The polymerization pressure is usually from atmospheric pressure to
10 kg / cm ² , preferably atmospheric pressure to 5 kg / c
m ² , the polymerization temperature is usually 30 to 90 ° C., preferably 4
It is 0 to 80 ° C. Polymerization time is usually 30 minutes to 10 hours,
It is preferably 1 to 5 hours.

The gas phase polymerization is carried out under the temperature and pressure conditions where propylene or a mixed monomer of propylene and another α-olefin is introduced and the gas phase state can be maintained. α-
Examples of the olefin include ethylene, butene-1, 4-methylpentene-1 and the like. The polymerization pressure is usually atmospheric pressure to 10 kg / cm ² , preferably atmospheric pressure to 5 kg / cm ² , and the polymerization temperature is usually 50 to 95.
C., preferably 65 to 90.degree. The polymerization time is usually 30 minutes to 10 hours, preferably 1 to 5 hours.

It is preferable to perform bulk polymerization in the first stage and slurry polymerization in the second stage. After the completion of polymerization, as a post-treatment step, the polymer solution slurry may be poured into a solvent such as ethanol, filtered and dried to obtain a polymer. Alternatively, the polymer slurry can be directly filtered and dried to obtain a polymer. In the slurry polymerization, a low molecular weight product produced as a by-product can be removed in a post-treatment step, and the tackiness of the resulting block copolymer can be improved.

[0019]

According to the present invention, a propylene block copolymer having a high molecular weight of a rubbery copolymer component of propylene and α-olefin can be produced with high copolymerization activity.

[0020]

EXAMPLES Examples of the present invention will be described below. In the examples, the copolymerization yield is a polymer weight ratio in the second stage in the total polymer. The weight average molecular weight was determined by gel permeation chromatography (GPC). The measurement was performed using 150CV type GPC manufactured by Waters. (Solvent _o- dichlorobenzene (0.3%
BHT included), column SHODEXAT-80M ×
2, temperature 145 ℃, sample concentration 0.03wt%, flow rate
1.0 ml / min. ) The ethylene content of the xylene-soluble part was determined by IR.
The sample to be measured was prepared on the hot press hot plate with a thickness of 0.2 mm between two ferro plates and a Teflon sheet of about 0.
Place 5g, melt at 180 ℃ for 1 minute without pressure,
Subsequently, after pressurizing at 50 kg / cm ² G for 1 minute, it was rapidly cooled in a water tank to prepare a film. The IR measurement was carried out by using a Gardner calibration curve (I. J. Gardner et. Al., Ru.
bberChem. & Tech. vol. 44,10
51p. (1971)) was used, and it calculated | required from the intensity ratio of 1155 cm < ^-1 > and 720 cm < ^-1 >.

Example 1 SB-12 manufactured by Tosoh Akzo Co., Ltd. as a solid containing titanium trichloride was placed in an autoclave with an internal volume of 2 L equipped with a stirrer.
After attaching a glass ampoule containing 138 mg of the above, the autoclave was replaced with nitrogen. Next, an autoclave was charged with 1.79 ml of an n-heptane solution containing 1.79 mmol of diethylaluminum chloride (DEAC). Then, after introducing 1.5 kg / cm ² G of hydrogen, 1200 ml of liquid propylene was introduced and the autoclave was shaken. Raise the temperature inside the autoclave to 65 ° C,
When the stirring was started, the glass ampoule containing the solid catalyst component was crushed, and the first stage bulk polymerization was carried out at 65 ° C. for 20 minutes.

After completion of the polymerization, unreacted propylene gas was released and the inside of the autoclave was replaced with nitrogen. The yield of homopolypropylene produced at this time was 57.4 g.
Subsequently, under nitrogen, 1.98 mmol of methylaluminoxane (polymethylaluminoxane manufactured by Tosoh Akzo).
Was injected with 700 ml of heptane. After that, ethylene and propylene were fed into the autoclave under atmospheric pressure at 125 ml / min. And 750 ml / min.
The second stage slurry copolymerization was carried out at 65 ° C. for 120 minutes while feeding at the rate. After completion of the polymerization, the polymerization slurry was put into 1 L of ethanol to precipitate the polymer,
77.3 g of the copolymer was recovered by filtration and drying.
5 g of the copolymer was dissolved in 500 ml of p-xylene by heating, and then left at room temperature for 12 hours, then the soluble part and the insoluble part were separated by centrifugation, and the soluble part was put into 2 L of ethanol to cause precipitation. It was recovered by filtration and drying. The results are shown in Table 1.

Example 2 Polymerization was carried out in the same manner as in Example 1 except that the amount of methylaluminoxane added in the second step was 4.94 mmol. The results are shown in Table 1.

Comparative Example Polymerization was carried out in the same manner as in Example 1 except that methylaluminoxane was not added in the second stage. The results are shown in Table 1.
It was shown to.

[Brief description of drawings]

FIG. 1 is a flow chart showing a polymerization method of the present invention and a step of preparing a catalyst solid component used in the polymerization.

[Table 1]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichiro Yamada 8-1 Goi Minamikaigan, Ichihara City, Chiba Ube Industries Ltd. Chiba Research Institute

Claims (1)

[Claims] 1. A solid containing titanium trichloride and the formula AlR _3-n.
20 ° C. using a catalyst system composed of an alkylaluminum compound represented by X _n (wherein R is an alkyl group having 1 to 8 carbon atoms, X is a halogen, and n is a number greater than 0 and less than 3). The weight average molecular weight of the xylene soluble part is 400,
In the method for producing a propylene block copolymer having a molecular weight of 000 or more, propylene or propylene and a small amount of another α-olefin are polymerized in the first step, and subsequently,
Without deactivating the above catalyst system, alkylaluminoxane was added in the second stage to obtain propylene and α other than propylene.
-A method for producing a propylene block copolymer, which comprises polymerizing with an olefin.