JPH0940709A - Production of ethylene/aromatic vinyl compound copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an ethylene/aromatic vinyl compound copolymer only under gentle reaction conditions in an activity high enough for industrial production by polymerizing ethylene and an aromatic vinyl compound in the presence of a catalyst comprising a specified Zr or Hf compound and a specified promoter. SOLUTION: Ethylene is copolymerized with an aromatic vinyl compound in the presence of a catalyst comprising a metal compound represented by the formula [M is Zr or Hf; Cp1 and Cp2 are each unsubstituted cyclopentadienyl; Y is -CH2 -, -CMe2 -, -CPh2 -, -SiH2 -, -SiMe2 -, -SiPh2 - or the like (Me is methyl; and Ph is phenyl); and x is H, a halogen, an alkyl or an aryl] and an organoaluminum compound and/or a boron compound. According to this production process, an ethylene/aromatic vinyl compound copolymer (e.g. ethylene/styrene copolymer) can be produced under conditions milder than those of prior art in an activity high enough for industrial production.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing an ethylene-aromatic vinyl compound copolymer.

[0002]

A copolymer of ethylene and an aromatic vinyl compound such as styrene is a so-called heterogeneous Ziegler-type copolymer.
Investigations have been made using Natta catalysts. In addition,
6-049132, JP-A3-163088, JP-A-7-5361
Japanese Unexamined Patent Publication No. 8 describes a method for producing an ethylene-styrene copolymer using a so-called homogeneous Ziegler-Natta catalyst system composed of a specific transition metal compound catalyst and an organoaluminum compound as a cocatalyst.

[0003]

In the production of ethylene-aromatic vinyl compound copolymers, conventional heterogeneous Ziegler-Natta catalyst systems have low activity, low styrene content and high homopolymer content. It is not practical because it contains and does not have a uniform composition. Further, in the recent homogeneous Ziegler-Natta system, for example, in the method disclosed in Japanese Patent Laid-Open No. 6-049132, the polymer yield per unit metal is low, and a large amount of organoaluminum compound is required, so that it is industrially used. It cannot be said that it is a simple manufacturing method. Similarly, in the method disclosed in Japanese Patent Application Laid-Open No. 3-163088 and Japanese Patent Application Laid-Open No. 7-53618, in addition to the need for a large amount of organoaluminum, the object under mild reaction conditions as illustrated in this comparative example is In addition to the ethylene-styrene copolymer as described above, a large amount of syndiotactic polystyrene is by-produced, so it cannot be said to be an efficient production method.

[0004]

DISCLOSURE OF THE INVENTION An object of the present invention is to overcome the drawbacks of conventional transition metal compound catalysts with respect to the production of ethylene-styrene copolymer, and to provide a method suitable for more industrial production. As a result, it has been found that by using a specific metal compound composed of zirconium or hafnium as a catalyst, an ethylene-styrene copolymer alone can be produced with a high activity suitable for industrialization under a reaction condition milder than that of a conventional method. It was

The method for producing an ethylene-styrene copolymer of the present invention comprises the following general formula (I):

Embedded image The method is characterized by using a catalyst system comprising zirconium or a hafnium metal compound and a co-catalyst as shown in FIG. Here, M is zirconium or hafnium, and Cp1 and Cp2 each represent a cyclopentadienyl group having no substituent or an alkyl substituent having no ring structure.
Or two cyclopentadienyl groups. C
p1 and Cp2 may be the same or different from each other. The substituent is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, or a t-butyl group, and they do not have a ring structure with each other. It is more preferable that both Cp1 and Cp2 are cyclopentadienyl groups having no substituent. Y is a group that crosslinks Cp1 and Cp2, and has a role of making the angle formed by Cp1, M, and Cp2, a so-called bite angle, smaller than that in the state where Cp1 and Cp2 are not crosslinked. Y has a bond with Cp1 or Cp2 and is hydrogen, or a carbon having a substituent of an alkyl group, silicon, germanium or boron, but the substituents may be different from each other or the same, but a cyclic structure such as a cyclohexyl group may be formed. You may have. For example, -CH2-, -CMe2
-, -CPh2-, -SiH2-, -SiMe2-, -S
iPh2-, etc. (Here, Me is a methyl group, Ph
Represents a phenyl group. ) X is hydrogen, halogen such as chlorine and bromine, alkyl group such as methyl group and ethyl group, aryl group such as phenyl group and the like.

In the present invention, an organoaluminum compound and / or a boron compound is used as a cocatalyst together with the above metal compound. Alumoxane is suitable as the organoaluminum compound used as a cocatalyst. Alumoxane is represented by the following general formula (II) or (III)

Embedded image

Embedded image Is a cyclic or chain compound represented by the formula (wherein each R is independently an alkyl group having 1 to 5 carbon atoms, most preferably a methyl group having 1 carbon atom, m and n are integers of 2 to 100). If necessary, a mixture of these different alumoxanes may be used. Also, these alumoxanes and alkylaluminums such as trimethylaluminum,
You may use triethyl aluminum, triisobutyl aluminum, dimethyl aluminum chloride, etc. together.

The boron compound used as a cocatalyst is N,
N-dimethylanilinium tetra (pentafluorophenyl) borate, trityl tetra (pentafluorophenyl) borate, tri (pentafluorophenyl) borate and the like. The boron compound and the organoaluminum compound may be used at the same time. Particularly when a boron compound is used as a cocatalyst, the addition of an alkylaluminum compound such as triisobutylaluminum is effective for removing impurities such as water contained in the polymerization system, which adversely affect the polymerization.

Examples of the aromatic vinyl compound include styrene and various substituted styrenes such as p-methylstyrene, o-methylstyrene, pt-butylstyrene and p-methylstyrene.
-Chlorostyrene, o-chlorostyrene and the like,
Further, a compound having a plurality of vinyl groups in one molecule such as divinylbenzene may be mentioned, but preferably styrene,
p-Methylstyrene is used, particularly preferably styrene.

In producing the copolymer of the present invention, ethylene, the aromatic vinyl compound exemplified above, the metal compound and the cocatalyst are brought into contact with ethylene and the aromatic vinyl compound, but a liquid monomer is used without using a solvent. There is a method of polymerizing in-, a method of using a saturated aliphatic or aromatic hydrocarbon alone or a mixed solvent of pentane, hexane, heptane, cyclohexane, benzene, toluene, xylene, chloro-substituted benzene, chloro-substituted toluene and the like. Further, if necessary, a method such as batch polymerization, continuous polymerization, batch polymerization, or preliminary polymerization can be used.

The polymerization temperature is suitably -78 ° C to 200 ° C, preferably 0 ° C to 140 ° C. A polymerization temperature lower than -78 ° C is industrially disadvantageous, and a temperature above 200 ° C is not suitable because decomposition of the metal compound occurs. When an organoaluminum compound is used as a co-catalyst, the aluminum atom / metal atom ratio is 0.1 to 100,000 with respect to the zirconium or hafnium metal compound.
It is preferably used in a ratio of 1 to 1000. If it is less than 0.1, the metal compound cannot be activated effectively and 100
If it exceeds 000, it is economically disadvantageous. When a boron compound is used as a cocatalyst, it is used at a boron atom / metal atom ratio of 0.01 to 100, but preferably at a ratio of 0.01.
1 to 10, particularly preferably 1 is used. If it is less than 0.01, the metal compound of zirconium or hafnium cannot be effectively activated, and if it exceeds 100, it is economically disadvantageous. The metal compound and the co-catalyst are mixed outside the polymerization tank,
They may be prepared or mixed in a tank at the time of polymerization.

[0011]

The present invention will be described below with reference to examples and comparative examples, but the present invention is not limited to the examples. In the chemical formulas below, Cp represents a cyclopentadienyl group, Me represents a methyl group, Bu represents a butyl group, and Flu represents a fluorenyl group. Example 1 In an autoclave having a capacity of 120 ml which was replaced with nitrogen, {Cp-C (Me) ₂ -C represented by the following chemical formula (IV) was used.
p} ZrCl ₂ 23 μmol, methylalumoxane (manufactured by Toso-Akzo, MMAO-3A) 14 mmol based on Al atom, styrene 10 ml, toluene 16 ml
Immediately pressurize with ethylene.
The reaction was carried out at 50 ° C. for 1 hour while maintaining the atmospheric pressure. Polymerization was completed in the first 5 minutes in terms of ethylene consumption and exotherm. Due to the rapid polymerization, the pressure during the first 5 minutes remained at about 2 atm. After completion of the reaction, the pressure of ethylene was released, and the content liquid was put into a large excess of hydrochloric acid / methanol mixed liquid to recover the polymer. When the polymer was dried under reduced pressure at 60 ° C. for 10 hours, 10.6 g of the polymer was recovered.

Embedded image

Example 2 Polymerization was carried out in the same manner as in Example 1 except that the amount of metal compound was reduced to 8.4 μmol and the amount of methylalumoxane was reduced to 8.4 mmol. The initial rapid polymerization as in Example 1 was not observed, and the polymerization substantially proceeded at an ethylene pressure of 5 atm. 9.3 g of polymer was recovered.

Example 3 Ethylene pressure was adjusted to 10 atm and reaction temperature was room temperature (10 ° C.)
Polymerization was carried out in the same manner as in Example 2 except that the above was used to obtain 10.4 g of a white polymer.

Example 4 Polymerization was carried out in the same manner as in Example 2 except that the ethylene pressure was 10 atm and the reaction temperature was 90 ° C. 16.4 g
Of white polymer was obtained.

Example 5 {Cp represented by the following chemical formula (V) as a metal compound
Polymerization was performed in the same manner as in Example 2 except that 8.4 μmol of —Si (Me) ₂ —Cp} ZrCl ₂ was used,
7.5 g of white polymer was obtained.

[Chemical 6]

Example 6 As a metal compound, {2,4-Me ₂ Cp-SiMe ₂ -2,4-
Polymerization was performed in the same manner as in Example 1 except that 23 μmol of Me ₂ Cp} ZrCl ₂ was used, and 5.7 g of a white polymer was obtained.

[0017] As Example 7 metal compound _{{Cp-SiMe 2 -Cp} HfCl} 2
Polymerization was conducted in the same manner as in Example 1 except that 23 μmol of was used to obtain 2.0 g of a white polymer.

Comparative Example 1 {Fl represented by the following chemical formula (VI) as a metal compound
Polymerization was carried out in the same manner as in Example 1 except that 23 μmol of u-CMe ₂ -Cp} ZrCl ₂ and 14 mmol of methylalumoxane were used on the basis of Al atoms. The initial rapid polymerization as in Example 1 was not observed, and the polymerization substantially proceeded at an ethylene pressure of 5 atm. 1.0 g of white polymer was obtained.

[Chemical 7]

Comparative Example 2 The metal compound was replaced by {2,3,4,5-Me ₄ Cp-SiMe ₂ -2,3,
Polymerization was carried out in the same manner as in Example 1 except that 4,5-Me ₄ Cp} ZrCl ₂ was changed to 0.32 g of a white polymer.
I got

Comparative Example 3 A metal compound represented by the following chemical formula (VII) {2,3,4,5
_{-Me 4 Cp-SiMe 2 -N (} t-Bu)} TiCl 2
Polymerization was carried out in the same manner as in Example 1 except that
1.6 g of white polymer was obtained.

Embedded image

Comparative Example 4 Polymerization was carried out in the same manner as in Example 1 except that the metal compound was changed to {Cp-CMe ₂ -Cp} TiCl ₂ and the result was 0.1.
g of white polymer was obtained.

The polymers obtained in the respective examples and comparative examples were analyzed by the following means. ¹³ C-NMR was performed by JNM GX-270 manufactured by JEOL Ltd. using a mixed solvent of o-dichlorobenzene and heavy benzene or a heavy chloroform solvent. As a result, the polymers obtained in Examples 1 to 7 and Comparative Example 1 were the same ethylene-styrene random copolymers as shown in FIG. This copolymer is a pseudo-random copolymer having no styrene-styrene-head-tail chain. Comparative Example 2
The polymer obtained in 1. was polyethylene. Comparative Example 3
In the polymer obtained in 1. above, large peaks of polyethylene and syndiotactic polystyrene were observed in addition to the above ethylene-styrene random copolymer. The polymer obtained in Comparative Example 4 was a mixture of polyethylene and syndiotactic polystyrene. The styrene content in the polymer was determined by ¹ H-NMR, and the instrument was a JNM GX-270 manufactured by JEOL Ltd. using a heavy chloroform solvent or 1,1,2,2-tetrachloroethane, and a phenyl group. The strength of the peak derived from the proton was compared with that of the proton peak derived from the alkyl group. The molecular weight is H manufactured by Tosoh Corporation.
CL-8020 is used, THF is used as a measurement solvent, and G
It was measured by the PC method. The above analysis results are summarized in Table 1.
Described in.

[0023]

[Table 1]

[0024]

According to the present invention, a cyclopentadienyl group (Cp) having no substituent and / or a cyclopentadienyl group (Cp ') having one or two alkyl substituents having no ring structure are used. By using a zirconium or hafnium metal compound having two crosslinked ligands as a catalyst, it is possible to produce only an ethylene-styrene copolymer with a high activity suitable for industrialization under a reaction condition milder than in the conventional method.

[Brief description of drawings]

FIG. 1 shows a ¹³ C-NMR spectrum of the ethylene-styrene random copolymer obtained in Example 1.

Claims (2)

[Claims] 1. A method for producing an ethylene-aromatic vinyl compound copolymer, which comprises polymerizing using a metal compound represented by the following general formula (I) and an organoaluminum compound and / or a boron compound. . Embedded image (Where M is zirconium or hafnium,
Cp1 and Cp2 are a cyclopentadienyl group having no substituent or a cyclopentadienyl group having one or two alkyl substituents having no ring structure. Cp1 and Cp2 may be the same or different from each other. Y is carbon, silicon, germanium or boron having a hydrogen atom or a substituent of an alkyl group, which has a bond with Cp1 and Cp2, but the substituents may be different from each other or the same, but a cyclic structure such as a cyclohexyl group. May have. X is a halogen such as hydrogen, chlorine or bromine, a methyl group,
Examples include an alkyl group such as an ethyl group and an aryl group such as a phenyl group. ) 2. The Cp1 and Cp2 of the chemical formula 1 according to claim 1.
Is a cyclopentadienyl group having no substituents, wherein the ethylene-aromatic vinyl compound copolymer is produced.